[5/5] drm: add syncobj timeline support v2

Submitted by Zhou, David(ChunMing) on Aug. 23, 2018, 8:25 a.m.

Details

Message ID 20180823082542.2998-5-david1.zhou@amd.com
State New
Headers show
Series "Series without cover letter" ( rev: 1 ) in AMD X.Org drivers

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Commit Message

Zhou, David(ChunMing) Aug. 23, 2018, 8:25 a.m.
VK_KHR_timeline_semaphore:
This extension introduces a new type of semaphore that has an integer payload
identifying a point in a timeline. Such timeline semaphores support the
following operations:
   * Host query - A host operation that allows querying the payload of the
     timeline semaphore.
   * Host wait - A host operation that allows a blocking wait for a
     timeline semaphore to reach a specified value.
   * Device wait - A device operation that allows waiting for a
     timeline semaphore to reach a specified value.
   * Device signal - A device operation that allows advancing the
     timeline semaphore to a specified value.

Since it's a timeline, that means the front time point(PT) always is signaled before the late PT.
a. signal PT design:
Signal PT fence N depends on PT[N-1] fence and signal opertion fence, when PT[N] fence is signaled,
the timeline will increase to value of PT[N].
b. wait PT design:
Wait PT fence is signaled by reaching timeline point value, when timeline is increasing, will compare
wait PTs value with new timeline value, if PT value is lower than timeline value, then wait PT will be
signaled, otherwise keep in list. semaphore wait operation can wait on any point of timeline,
so need a RB tree to order them. And wait PT could ahead of signal PT, we need a sumission fence to
perform that.

v2:
1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
2. move unexposed denitions to .c file. (Daniel Vetter)
3. split up the change to drm_syncobj_find_fence() in a separate patch. (Christian)
4. split up the change to drm_syncobj_replace_fence() in a separate patch.
5. drop the submission_fence implementation and instead use wait_event() for that. (Christian)
6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)

TODO:
1. CPU query and wait on timeline semaphore.
2. test application (Daniel Vetter)

Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Cc: Christian Konig <christian.koenig@amd.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Daniel Rakos <Daniel.Rakos@amd.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/drm_syncobj.c | 383 +++++++++++++++++++++++++++++++++++++++---
 include/drm/drm_syncobj.h     |  28 +++
 include/uapi/drm/drm.h        |   1 +
 3 files changed, 389 insertions(+), 23 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 6227df2cc0a4..f738d78edf65 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -56,6 +56,44 @@ 
 #include "drm_internal.h"
 #include <drm/drm_syncobj.h>
 
+struct drm_syncobj_stub_fence {
+	struct dma_fence base;
+	spinlock_t lock;
+};
+
+static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
+{
+        return "syncobjstub";
+}
+
+static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
+{
+    return !dma_fence_is_signaled(fence);
+}
+
+static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
+	.get_driver_name = drm_syncobj_stub_fence_get_name,
+	.get_timeline_name = drm_syncobj_stub_fence_get_name,
+	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
+	.release = NULL,
+};
+
+struct drm_syncobj_wait_pt {
+	struct drm_syncobj_stub_fence base;
+	u64    value;
+	struct rb_node   node;
+};
+struct drm_syncobj_signal_pt {
+	struct drm_syncobj_stub_fence base;
+	struct dma_fence *signal_fence;
+	struct dma_fence *pre_pt_base;
+	struct dma_fence_cb signal_cb;
+	struct dma_fence_cb pre_pt_cb;
+	struct drm_syncobj *syncobj;
+	u64    value;
+	struct list_head list;
+};
+
 /**
  * drm_syncobj_find - lookup and reference a sync object.
  * @file_private: drm file private pointer
@@ -137,6 +175,150 @@  void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
 	spin_unlock(&syncobj->lock);
 }
 
+static void drm_syncobj_timeline_signal_wait_pts(struct drm_syncobj *syncobj)
+{
+	struct rb_node *node = NULL;
+	struct drm_syncobj_wait_pt *wait_pt = NULL;
+
+	spin_lock(&syncobj->lock);
+	for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
+	    node != NULL; ) {
+		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
+		node = rb_next(node);
+		if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
+			dma_fence_signal(&wait_pt->base.base);
+			rb_erase(&wait_pt->node,
+				 &syncobj->syncobj_timeline.wait_pt_tree);
+			RB_CLEAR_NODE(&wait_pt->node);
+			/* kfree(wait_pt) is excuted by fence put */
+			dma_fence_put(&wait_pt->base.base);
+		} else {
+			/* the loop is from left to right, the later entry value is
+			 * bigger, so don't need to check any more */
+			break;
+		}
+	}
+	spin_unlock(&syncobj->lock);
+}
+
+
+static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
+{
+	struct dma_fence *fence = NULL;
+	struct drm_syncobj *syncobj;
+
+	fence = signal_pt->signal_fence;
+	signal_pt->signal_fence = NULL;
+	dma_fence_put(fence);
+	fence = signal_pt->pre_pt_base;
+	signal_pt->pre_pt_base = NULL;
+	dma_fence_put(fence);
+
+	syncobj = signal_pt->syncobj;
+	spin_lock(&syncobj->lock);
+	list_del(&signal_pt->list);
+	syncobj->syncobj_timeline.timeline = signal_pt->value;
+	spin_unlock(&syncobj->lock);
+	/* kfree(signal_pt) will be  executed by below fence put */
+	dma_fence_put(&signal_pt->base.base);
+	drm_syncobj_timeline_signal_wait_pts(syncobj);
+}
+static void pt_signal_fence_func(struct dma_fence *fence,
+				 struct dma_fence_cb *cb)
+{
+	struct drm_syncobj_signal_pt *signal_pt =
+		container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
+
+	if (signal_pt->pre_pt_base &&
+	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
+		return;
+
+	pt_fence_cb(signal_pt);
+}
+static void pt_pre_fence_func(struct dma_fence *fence,
+				 struct dma_fence_cb *cb)
+{
+	struct drm_syncobj_signal_pt *signal_pt =
+		container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
+
+	if (signal_pt->signal_fence &&
+	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
+		return;
+
+	pt_fence_cb(signal_pt);
+}
+
+static int drm_syncobj_timeline_replace_fence(struct drm_syncobj *syncobj,
+					      struct dma_fence *fence,
+					      u64 point)
+{
+	struct drm_syncobj_signal_pt *signal_pt =
+		kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
+	struct drm_syncobj_signal_pt *tail_pt;
+	struct dma_fence *tail_pt_fence = NULL;
+	int ret = 0;
+
+	if (!signal_pt)
+		return -ENOMEM;
+	if (syncobj->syncobj_timeline.signal_point >= point) {
+		DRM_WARN("A later signal is ready!");
+		goto out;
+	}
+	if (fence)
+		dma_fence_get(fence);
+	spin_lock(&syncobj->lock);
+	spin_lock_init(&signal_pt->base.lock);
+	dma_fence_init(&signal_pt->base.base,
+		       &drm_syncobj_stub_fence_ops,
+		       &signal_pt->base.lock,
+		       syncobj->syncobj_timeline.timeline_context, point);
+	signal_pt->signal_fence =
+		rcu_dereference_protected(fence,
+					  lockdep_is_held(&fence->lock));
+	if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
+		tail_pt = list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
+					  struct drm_syncobj_signal_pt, list);
+		tail_pt_fence = &tail_pt->base.base;
+		if (dma_fence_is_signaled(tail_pt_fence))
+			tail_pt_fence = NULL;
+	}
+	if (tail_pt_fence)
+		signal_pt->pre_pt_base =
+			dma_fence_get(rcu_dereference_protected(tail_pt_fence,
+								lockdep_is_held(&tail_pt_fence->lock)));
+
+	signal_pt->value = point;
+	syncobj->syncobj_timeline.signal_point = point;
+	signal_pt->syncobj = syncobj;
+	INIT_LIST_HEAD(&signal_pt->list);
+	list_add_tail(&signal_pt->list, &syncobj->syncobj_timeline.signal_pt_list);
+	spin_unlock(&syncobj->lock);
+	wake_up_all(&syncobj->syncobj_timeline.wq);
+	/**
+	 * Every pt is depending on signal fence and previous pt fence, add
+	 * callbacks to them
+	 */
+	if (!dma_fence_is_signaled(signal_pt->signal_fence))
+		dma_fence_add_callback(signal_pt->signal_fence,
+				       &signal_pt->signal_cb,
+				       pt_signal_fence_func);
+	else
+		pt_signal_fence_func(signal_pt->signal_fence,
+				     &signal_pt->signal_cb);
+	if (signal_pt->pre_pt_base && !dma_fence_is_signaled(signal_pt->pre_pt_base))
+		dma_fence_add_callback(signal_pt->pre_pt_base,
+				       &signal_pt->pre_pt_cb,
+				       pt_pre_fence_func);
+	else
+		pt_pre_fence_func(signal_pt->pre_pt_base, &signal_pt->pre_pt_cb);
+
+
+	return 0;
+out:
+	kfree(signal_pt);
+	return ret;
+}
+
 /**
  * drm_syncobj_replace_fence - replace fence in a sync object.
  * @syncobj: Sync object to replace fence in
@@ -152,6 +334,11 @@  void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
 	struct dma_fence *old_fence;
 	struct drm_syncobj_cb *cur, *tmp;
 
+	if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
+		drm_syncobj_timeline_replace_fence(syncobj, fence,
+						   point);
+		return;
+	}
 	if (fence)
 		dma_fence_get(fence);
 
@@ -174,28 +361,6 @@  void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
 }
 EXPORT_SYMBOL(drm_syncobj_replace_fence);
 
-struct drm_syncobj_stub_fence {
-	struct dma_fence base;
-	spinlock_t lock;
-};
-
-static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
-{
-        return "syncobjstub";
-}
-
-static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
-{
-    return !dma_fence_is_signaled(fence);
-}
-
-static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
-	.get_driver_name = drm_syncobj_stub_fence_get_name,
-	.get_timeline_name = drm_syncobj_stub_fence_get_name,
-	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
-	.release = NULL,
-};
-
 static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
 {
 	struct drm_syncobj_stub_fence *fence;
@@ -215,6 +380,121 @@  static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
 	return 0;
 }
 
+static struct drm_syncobj_wait_pt *
+drm_syncobj_timeline_lookup_wait_pt(struct drm_syncobj *syncobj, u64 point)
+{
+    struct rb_node *node = syncobj->syncobj_timeline.wait_pt_tree.rb_node;
+    struct drm_syncobj_wait_pt *wait_pt = NULL;
+
+
+    spin_lock(&syncobj->lock);
+    while(node) {
+	    int result = point - wait_pt->value;
+
+	    wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
+	    if (result < 0)
+		    node = node->rb_left;
+	    else if (result > 0)
+		    node = node->rb_right;
+	    else
+		    break;
+    }
+    spin_unlock(&syncobj->lock);
+
+    return wait_pt;
+}
+
+static struct drm_syncobj_wait_pt *
+drm_syncobj_timeline_create_wait_pt(struct drm_syncobj *syncobj, u64 point)
+{
+	struct drm_syncobj_wait_pt *wait_pt;
+	struct rb_node **new = &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
+
+	wait_pt = kzalloc(sizeof(*wait_pt), GFP_KERNEL);
+	if (!wait_pt)
+		return NULL;
+	spin_lock_init(&wait_pt->base.lock);
+	dma_fence_init(&wait_pt->base.base,
+		       &drm_syncobj_stub_fence_ops,
+		       &wait_pt->base.lock,
+		       syncobj->syncobj_timeline.timeline_context, point);
+	wait_pt->value = point;
+
+	/* wait pt must be in an order, so that we can easily lookup and signal
+	 * it */
+	spin_lock(&syncobj->lock);
+	if (point <= syncobj->syncobj_timeline.timeline)
+		dma_fence_signal(&wait_pt->base.base);
+	while(*new) {
+		struct drm_syncobj_wait_pt *this =
+			rb_entry(*new, struct drm_syncobj_wait_pt, node);
+		int result = wait_pt->value - this->value;
+
+		parent = *new;
+		if (result < 0)
+			new = &((*new)->rb_left);
+		else if (result > 0)
+			new = &((*new)->rb_right);
+		else
+			goto exist;
+	}
+
+	rb_link_node(&wait_pt->node, parent, new);
+	rb_insert_color(&wait_pt->node, &syncobj->syncobj_timeline.wait_pt_tree);
+	spin_unlock(&syncobj->lock);
+	return wait_pt;
+exist:
+	spin_unlock(&syncobj->lock);
+	dma_fence_put(&wait_pt->base.base);
+	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
+	return wait_pt;
+}
+
+static struct dma_fence *
+drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 point, u64 flag)
+{
+	struct drm_syncobj_wait_pt *wait_pt;
+
+	/* already signaled, simply return a signaled stub fence */
+	if (point <= syncobj->syncobj_timeline.timeline) {
+		struct drm_syncobj_stub_fence *fence;
+
+		fence = kzalloc(sizeof(*fence), GFP_KERNEL);
+		if (fence == NULL)
+			return NULL;
+
+		spin_lock_init(&fence->lock);
+		dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
+			       &fence->lock, 0, 0);
+		dma_fence_signal(&fence->base);
+		return &fence->base;
+	}
+
+	/* check if the wait pt exists */
+	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
+	if (!wait_pt) {
+		/* This is a new wait pt, so create it */
+		wait_pt = drm_syncobj_timeline_create_wait_pt(syncobj, point);
+		if (!wait_pt)
+			return NULL;
+	}
+	if (wait_pt) {
+		struct dma_fence *fence;
+		int ret =
+			wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
+				wait_pt->value <= syncobj->syncobj_timeline.signal_point,
+				msecs_to_jiffies(10000)); /* wait 10s */
+
+		if (ret <= 0)
+			return NULL;
+		rcu_read_lock();
+		fence = dma_fence_get_rcu(&wait_pt->base.base);
+		rcu_read_unlock();
+		return fence;
+	}
+	return NULL;
+}
+
 /**
  * drm_syncobj_find_fence - lookup and reference the fence in a sync object
  * @file_private: drm file private pointer
@@ -240,7 +520,17 @@  int drm_syncobj_find_fence(struct drm_file *file_private,
 	if (!syncobj)
 		return -ENOENT;
 
-	*fence = drm_syncobj_fence_get(syncobj);
+	if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
+		/* NORMAL syncobj doesn't care point value */
+		WARN_ON(point != 0);
+		*fence = drm_syncobj_fence_get(syncobj);
+	} else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
+		*fence = drm_syncobj_timeline_point_get(syncobj, point,
+							DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT);
+	} else {
+		DRM_ERROR("Don't support this type syncobj\n");
+		*fence = NULL;
+	}
 	if (!*fence) {
 		ret = -EINVAL;
 	}
@@ -249,6 +539,34 @@  int drm_syncobj_find_fence(struct drm_file *file_private,
 }
 EXPORT_SYMBOL(drm_syncobj_find_fence);
 
+static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
+				      struct drm_syncobj_timeline *syncobj_timeline)
+{
+	struct rb_node *node = NULL;
+	struct drm_syncobj_wait_pt *wait_pt = NULL;
+	struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
+
+	spin_lock(&syncobj->lock);
+	for(node = rb_first(&syncobj_timeline->wait_pt_tree);
+	    node != NULL; ) {
+		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
+		node = rb_next(node);
+		rb_erase(&wait_pt->node,
+			 &syncobj_timeline->wait_pt_tree);
+		RB_CLEAR_NODE(&wait_pt->node);
+		/* kfree(wait_pt) is excuted by fence put */
+		dma_fence_put(&wait_pt->base.base);
+	}
+	list_for_each_entry_safe(signal_pt, tmp,
+				 &syncobj_timeline->signal_pt_list, list) {
+		list_del(&signal_pt->list);
+		dma_fence_put(signal_pt->signal_fence);
+		dma_fence_put(signal_pt->pre_pt_base);
+		dma_fence_put(&signal_pt->base.base);
+	}
+	spin_unlock(&syncobj->lock);
+}
+
 /**
  * drm_syncobj_free - free a sync object.
  * @kref: kref to free.
@@ -261,10 +579,23 @@  void drm_syncobj_free(struct kref *kref)
 						   struct drm_syncobj,
 						   refcount);
 	drm_syncobj_replace_fence(syncobj, NULL, 0);
+	drm_syncobj_timeline_fini(syncobj, &syncobj->syncobj_timeline);
 	kfree(syncobj);
 }
 EXPORT_SYMBOL(drm_syncobj_free);
 
+static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
+				      *syncobj_timeline)
+{
+	syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
+	syncobj_timeline->timeline = 0;
+	syncobj_timeline->signal_point = 0;
+	init_waitqueue_head(&syncobj_timeline->wq);
+
+	syncobj_timeline->wait_pt_tree = RB_ROOT;
+	INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
+}
+
 /**
  * drm_syncobj_create - create a new syncobj
  * @out_syncobj: returned syncobj
@@ -290,6 +621,12 @@  int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
 	kref_init(&syncobj->refcount);
 	INIT_LIST_HEAD(&syncobj->cb_list);
 	spin_lock_init(&syncobj->lock);
+	if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) {
+		syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
+		drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
+	} else {
+		syncobj->type = DRM_SYNCOBJ_TYPE_NORMAL;
+	}
 
 	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
 		ret = drm_syncobj_assign_null_handle(syncobj);
diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
index 335ec501001a..342b3ced3e56 100644
--- a/include/drm/drm_syncobj.h
+++ b/include/drm/drm_syncobj.h
@@ -30,6 +30,25 @@ 
 
 struct drm_syncobj_cb;
 
+enum drm_syncobj_type {
+	DRM_SYNCOBJ_TYPE_NORMAL,
+	DRM_SYNCOBJ_TYPE_TIMELINE
+};
+
+struct drm_syncobj_timeline {
+	wait_queue_head_t	wq;
+	u64 timeline_context;
+	/**
+	 * @timeline: syncobj timeline
+	 */
+	u64 timeline;
+	u64 signal_point;
+
+
+	struct rb_root wait_pt_tree;
+	struct list_head signal_pt_list;
+};
+
 /**
  * struct drm_syncobj - sync object.
  *
@@ -40,6 +59,15 @@  struct drm_syncobj {
 	 * @refcount: Reference count of this object.
 	 */
 	struct kref refcount;
+	/**
+	 * @type: indicate syncobj type
+	 */
+	enum drm_syncobj_type type;
+	/**
+	 * @syncobj_timeline: timeline
+	 */
+	struct drm_syncobj_timeline syncobj_timeline;
+
 	/**
 	 * @fence:
 	 * NULL or a pointer to the fence bound to this object.
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 300f336633f2..cebdb2541eb7 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -717,6 +717,7 @@  struct drm_prime_handle {
 struct drm_syncobj_create {
 	__u32 handle;
 #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
+#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
 	__u32 flags;
 };
 

Comments

On Thu, Aug 23, 2018 at 04:25:42PM +0800, Chunming Zhou wrote:
> VK_KHR_timeline_semaphore:
> This extension introduces a new type of semaphore that has an integer payload
> identifying a point in a timeline. Such timeline semaphores support the
> following operations:
>    * Host query - A host operation that allows querying the payload of the
>      timeline semaphore.
>    * Host wait - A host operation that allows a blocking wait for a
>      timeline semaphore to reach a specified value.
>    * Device wait - A device operation that allows waiting for a
>      timeline semaphore to reach a specified value.
>    * Device signal - A device operation that allows advancing the
>      timeline semaphore to a specified value.
> 
> Since it's a timeline, that means the front time point(PT) always is signaled before the late PT.
> a. signal PT design:
> Signal PT fence N depends on PT[N-1] fence and signal opertion fence, when PT[N] fence is signaled,
> the timeline will increase to value of PT[N].
> b. wait PT design:
> Wait PT fence is signaled by reaching timeline point value, when timeline is increasing, will compare
> wait PTs value with new timeline value, if PT value is lower than timeline value, then wait PT will be
> signaled, otherwise keep in list. semaphore wait operation can wait on any point of timeline,
> so need a RB tree to order them. And wait PT could ahead of signal PT, we need a sumission fence to
> perform that.
> 
> v2:
> 1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
> 2. move unexposed denitions to .c file. (Daniel Vetter)
> 3. split up the change to drm_syncobj_find_fence() in a separate patch. (Christian)
> 4. split up the change to drm_syncobj_replace_fence() in a separate patch.
> 5. drop the submission_fence implementation and instead use wait_event() for that. (Christian)
> 6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)

Depending upon how it's going to be used, this is the wrong thing to do.

> TODO:
> 1. CPU query and wait on timeline semaphore.
> 2. test application (Daniel Vetter)

I also had some more suggestions, around aligning the two concepts of
future fences and at least trying to merge the timeline and the other
fence (which really is just a special case of a timeline with only 1
slot).
-Daniel

> 
> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
> Cc: Christian Konig <christian.koenig@amd.com>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Daniel Rakos <Daniel.Rakos@amd.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> ---
>  drivers/gpu/drm/drm_syncobj.c | 383 +++++++++++++++++++++++++++++++++++++++---
>  include/drm/drm_syncobj.h     |  28 +++
>  include/uapi/drm/drm.h        |   1 +
>  3 files changed, 389 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 6227df2cc0a4..f738d78edf65 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -56,6 +56,44 @@
>  #include "drm_internal.h"
>  #include <drm/drm_syncobj.h>
>  
> +struct drm_syncobj_stub_fence {
> +	struct dma_fence base;
> +	spinlock_t lock;
> +};
> +
> +static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
> +{
> +        return "syncobjstub";
> +}
> +
> +static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
> +{
> +    return !dma_fence_is_signaled(fence);
> +}
> +
> +static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
> +	.get_driver_name = drm_syncobj_stub_fence_get_name,
> +	.get_timeline_name = drm_syncobj_stub_fence_get_name,
> +	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
> +	.release = NULL,
> +};
> +
> +struct drm_syncobj_wait_pt {
> +	struct drm_syncobj_stub_fence base;
> +	u64    value;
> +	struct rb_node   node;
> +};
> +struct drm_syncobj_signal_pt {
> +	struct drm_syncobj_stub_fence base;
> +	struct dma_fence *signal_fence;
> +	struct dma_fence *pre_pt_base;
> +	struct dma_fence_cb signal_cb;
> +	struct dma_fence_cb pre_pt_cb;
> +	struct drm_syncobj *syncobj;
> +	u64    value;
> +	struct list_head list;
> +};
> +
>  /**
>   * drm_syncobj_find - lookup and reference a sync object.
>   * @file_private: drm file private pointer
> @@ -137,6 +175,150 @@ void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
>  	spin_unlock(&syncobj->lock);
>  }
>  
> +static void drm_syncobj_timeline_signal_wait_pts(struct drm_syncobj *syncobj)
> +{
> +	struct rb_node *node = NULL;
> +	struct drm_syncobj_wait_pt *wait_pt = NULL;
> +
> +	spin_lock(&syncobj->lock);
> +	for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
> +	    node != NULL; ) {
> +		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
> +		node = rb_next(node);
> +		if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
> +			dma_fence_signal(&wait_pt->base.base);
> +			rb_erase(&wait_pt->node,
> +				 &syncobj->syncobj_timeline.wait_pt_tree);
> +			RB_CLEAR_NODE(&wait_pt->node);
> +			/* kfree(wait_pt) is excuted by fence put */
> +			dma_fence_put(&wait_pt->base.base);
> +		} else {
> +			/* the loop is from left to right, the later entry value is
> +			 * bigger, so don't need to check any more */
> +			break;
> +		}
> +	}
> +	spin_unlock(&syncobj->lock);
> +}
> +
> +
> +static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
> +{
> +	struct dma_fence *fence = NULL;
> +	struct drm_syncobj *syncobj;
> +
> +	fence = signal_pt->signal_fence;
> +	signal_pt->signal_fence = NULL;
> +	dma_fence_put(fence);
> +	fence = signal_pt->pre_pt_base;
> +	signal_pt->pre_pt_base = NULL;
> +	dma_fence_put(fence);
> +
> +	syncobj = signal_pt->syncobj;
> +	spin_lock(&syncobj->lock);
> +	list_del(&signal_pt->list);
> +	syncobj->syncobj_timeline.timeline = signal_pt->value;
> +	spin_unlock(&syncobj->lock);
> +	/* kfree(signal_pt) will be  executed by below fence put */
> +	dma_fence_put(&signal_pt->base.base);
> +	drm_syncobj_timeline_signal_wait_pts(syncobj);
> +}
> +static void pt_signal_fence_func(struct dma_fence *fence,
> +				 struct dma_fence_cb *cb)
> +{
> +	struct drm_syncobj_signal_pt *signal_pt =
> +		container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
> +
> +	if (signal_pt->pre_pt_base &&
> +	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
> +		return;
> +
> +	pt_fence_cb(signal_pt);
> +}
> +static void pt_pre_fence_func(struct dma_fence *fence,
> +				 struct dma_fence_cb *cb)
> +{
> +	struct drm_syncobj_signal_pt *signal_pt =
> +		container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
> +
> +	if (signal_pt->signal_fence &&
> +	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
> +		return;
> +
> +	pt_fence_cb(signal_pt);
> +}
> +
> +static int drm_syncobj_timeline_replace_fence(struct drm_syncobj *syncobj,
> +					      struct dma_fence *fence,
> +					      u64 point)
> +{
> +	struct drm_syncobj_signal_pt *signal_pt =
> +		kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
> +	struct drm_syncobj_signal_pt *tail_pt;
> +	struct dma_fence *tail_pt_fence = NULL;
> +	int ret = 0;
> +
> +	if (!signal_pt)
> +		return -ENOMEM;
> +	if (syncobj->syncobj_timeline.signal_point >= point) {
> +		DRM_WARN("A later signal is ready!");
> +		goto out;
> +	}
> +	if (fence)
> +		dma_fence_get(fence);
> +	spin_lock(&syncobj->lock);
> +	spin_lock_init(&signal_pt->base.lock);
> +	dma_fence_init(&signal_pt->base.base,
> +		       &drm_syncobj_stub_fence_ops,
> +		       &signal_pt->base.lock,
> +		       syncobj->syncobj_timeline.timeline_context, point);
> +	signal_pt->signal_fence =
> +		rcu_dereference_protected(fence,
> +					  lockdep_is_held(&fence->lock));
> +	if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
> +		tail_pt = list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
> +					  struct drm_syncobj_signal_pt, list);
> +		tail_pt_fence = &tail_pt->base.base;
> +		if (dma_fence_is_signaled(tail_pt_fence))
> +			tail_pt_fence = NULL;
> +	}
> +	if (tail_pt_fence)
> +		signal_pt->pre_pt_base =
> +			dma_fence_get(rcu_dereference_protected(tail_pt_fence,
> +								lockdep_is_held(&tail_pt_fence->lock)));
> +
> +	signal_pt->value = point;
> +	syncobj->syncobj_timeline.signal_point = point;
> +	signal_pt->syncobj = syncobj;
> +	INIT_LIST_HEAD(&signal_pt->list);
> +	list_add_tail(&signal_pt->list, &syncobj->syncobj_timeline.signal_pt_list);
> +	spin_unlock(&syncobj->lock);
> +	wake_up_all(&syncobj->syncobj_timeline.wq);
> +	/**
> +	 * Every pt is depending on signal fence and previous pt fence, add
> +	 * callbacks to them
> +	 */
> +	if (!dma_fence_is_signaled(signal_pt->signal_fence))
> +		dma_fence_add_callback(signal_pt->signal_fence,
> +				       &signal_pt->signal_cb,
> +				       pt_signal_fence_func);
> +	else
> +		pt_signal_fence_func(signal_pt->signal_fence,
> +				     &signal_pt->signal_cb);
> +	if (signal_pt->pre_pt_base && !dma_fence_is_signaled(signal_pt->pre_pt_base))
> +		dma_fence_add_callback(signal_pt->pre_pt_base,
> +				       &signal_pt->pre_pt_cb,
> +				       pt_pre_fence_func);
> +	else
> +		pt_pre_fence_func(signal_pt->pre_pt_base, &signal_pt->pre_pt_cb);
> +
> +
> +	return 0;
> +out:
> +	kfree(signal_pt);
> +	return ret;
> +}
> +
>  /**
>   * drm_syncobj_replace_fence - replace fence in a sync object.
>   * @syncobj: Sync object to replace fence in
> @@ -152,6 +334,11 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>  	struct dma_fence *old_fence;
>  	struct drm_syncobj_cb *cur, *tmp;
>  
> +	if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
> +		drm_syncobj_timeline_replace_fence(syncobj, fence,
> +						   point);
> +		return;
> +	}
>  	if (fence)
>  		dma_fence_get(fence);
>  
> @@ -174,28 +361,6 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>  }
>  EXPORT_SYMBOL(drm_syncobj_replace_fence);
>  
> -struct drm_syncobj_stub_fence {
> -	struct dma_fence base;
> -	spinlock_t lock;
> -};
> -
> -static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
> -{
> -        return "syncobjstub";
> -}
> -
> -static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
> -{
> -    return !dma_fence_is_signaled(fence);
> -}
> -
> -static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
> -	.get_driver_name = drm_syncobj_stub_fence_get_name,
> -	.get_timeline_name = drm_syncobj_stub_fence_get_name,
> -	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
> -	.release = NULL,
> -};
> -
>  static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>  {
>  	struct drm_syncobj_stub_fence *fence;
> @@ -215,6 +380,121 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>  	return 0;
>  }
>  
> +static struct drm_syncobj_wait_pt *
> +drm_syncobj_timeline_lookup_wait_pt(struct drm_syncobj *syncobj, u64 point)
> +{
> +    struct rb_node *node = syncobj->syncobj_timeline.wait_pt_tree.rb_node;
> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
> +
> +
> +    spin_lock(&syncobj->lock);
> +    while(node) {
> +	    int result = point - wait_pt->value;
> +
> +	    wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
> +	    if (result < 0)
> +		    node = node->rb_left;
> +	    else if (result > 0)
> +		    node = node->rb_right;
> +	    else
> +		    break;
> +    }
> +    spin_unlock(&syncobj->lock);
> +
> +    return wait_pt;
> +}
> +
> +static struct drm_syncobj_wait_pt *
> +drm_syncobj_timeline_create_wait_pt(struct drm_syncobj *syncobj, u64 point)
> +{
> +	struct drm_syncobj_wait_pt *wait_pt;
> +	struct rb_node **new = &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
> +
> +	wait_pt = kzalloc(sizeof(*wait_pt), GFP_KERNEL);
> +	if (!wait_pt)
> +		return NULL;
> +	spin_lock_init(&wait_pt->base.lock);
> +	dma_fence_init(&wait_pt->base.base,
> +		       &drm_syncobj_stub_fence_ops,
> +		       &wait_pt->base.lock,
> +		       syncobj->syncobj_timeline.timeline_context, point);
> +	wait_pt->value = point;
> +
> +	/* wait pt must be in an order, so that we can easily lookup and signal
> +	 * it */
> +	spin_lock(&syncobj->lock);
> +	if (point <= syncobj->syncobj_timeline.timeline)
> +		dma_fence_signal(&wait_pt->base.base);
> +	while(*new) {
> +		struct drm_syncobj_wait_pt *this =
> +			rb_entry(*new, struct drm_syncobj_wait_pt, node);
> +		int result = wait_pt->value - this->value;
> +
> +		parent = *new;
> +		if (result < 0)
> +			new = &((*new)->rb_left);
> +		else if (result > 0)
> +			new = &((*new)->rb_right);
> +		else
> +			goto exist;
> +	}
> +
> +	rb_link_node(&wait_pt->node, parent, new);
> +	rb_insert_color(&wait_pt->node, &syncobj->syncobj_timeline.wait_pt_tree);
> +	spin_unlock(&syncobj->lock);
> +	return wait_pt;
> +exist:
> +	spin_unlock(&syncobj->lock);
> +	dma_fence_put(&wait_pt->base.base);
> +	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
> +	return wait_pt;
> +}
> +
> +static struct dma_fence *
> +drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 point, u64 flag)
> +{
> +	struct drm_syncobj_wait_pt *wait_pt;
> +
> +	/* already signaled, simply return a signaled stub fence */
> +	if (point <= syncobj->syncobj_timeline.timeline) {
> +		struct drm_syncobj_stub_fence *fence;
> +
> +		fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> +		if (fence == NULL)
> +			return NULL;
> +
> +		spin_lock_init(&fence->lock);
> +		dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
> +			       &fence->lock, 0, 0);
> +		dma_fence_signal(&fence->base);
> +		return &fence->base;
> +	}
> +
> +	/* check if the wait pt exists */
> +	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
> +	if (!wait_pt) {
> +		/* This is a new wait pt, so create it */
> +		wait_pt = drm_syncobj_timeline_create_wait_pt(syncobj, point);
> +		if (!wait_pt)
> +			return NULL;
> +	}
> +	if (wait_pt) {
> +		struct dma_fence *fence;
> +		int ret =
> +			wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
> +				wait_pt->value <= syncobj->syncobj_timeline.signal_point,
> +				msecs_to_jiffies(10000)); /* wait 10s */
> +
> +		if (ret <= 0)
> +			return NULL;
> +		rcu_read_lock();
> +		fence = dma_fence_get_rcu(&wait_pt->base.base);
> +		rcu_read_unlock();
> +		return fence;
> +	}
> +	return NULL;
> +}
> +
>  /**
>   * drm_syncobj_find_fence - lookup and reference the fence in a sync object
>   * @file_private: drm file private pointer
> @@ -240,7 +520,17 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>  	if (!syncobj)
>  		return -ENOENT;
>  
> -	*fence = drm_syncobj_fence_get(syncobj);
> +	if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
> +		/* NORMAL syncobj doesn't care point value */
> +		WARN_ON(point != 0);
> +		*fence = drm_syncobj_fence_get(syncobj);
> +	} else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
> +		*fence = drm_syncobj_timeline_point_get(syncobj, point,
> +							DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT);
> +	} else {
> +		DRM_ERROR("Don't support this type syncobj\n");
> +		*fence = NULL;
> +	}
>  	if (!*fence) {
>  		ret = -EINVAL;
>  	}
> @@ -249,6 +539,34 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>  }
>  EXPORT_SYMBOL(drm_syncobj_find_fence);
>  
> +static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
> +				      struct drm_syncobj_timeline *syncobj_timeline)
> +{
> +	struct rb_node *node = NULL;
> +	struct drm_syncobj_wait_pt *wait_pt = NULL;
> +	struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
> +
> +	spin_lock(&syncobj->lock);
> +	for(node = rb_first(&syncobj_timeline->wait_pt_tree);
> +	    node != NULL; ) {
> +		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
> +		node = rb_next(node);
> +		rb_erase(&wait_pt->node,
> +			 &syncobj_timeline->wait_pt_tree);
> +		RB_CLEAR_NODE(&wait_pt->node);
> +		/* kfree(wait_pt) is excuted by fence put */
> +		dma_fence_put(&wait_pt->base.base);
> +	}
> +	list_for_each_entry_safe(signal_pt, tmp,
> +				 &syncobj_timeline->signal_pt_list, list) {
> +		list_del(&signal_pt->list);
> +		dma_fence_put(signal_pt->signal_fence);
> +		dma_fence_put(signal_pt->pre_pt_base);
> +		dma_fence_put(&signal_pt->base.base);
> +	}
> +	spin_unlock(&syncobj->lock);
> +}
> +
>  /**
>   * drm_syncobj_free - free a sync object.
>   * @kref: kref to free.
> @@ -261,10 +579,23 @@ void drm_syncobj_free(struct kref *kref)
>  						   struct drm_syncobj,
>  						   refcount);
>  	drm_syncobj_replace_fence(syncobj, NULL, 0);
> +	drm_syncobj_timeline_fini(syncobj, &syncobj->syncobj_timeline);
>  	kfree(syncobj);
>  }
>  EXPORT_SYMBOL(drm_syncobj_free);
>  
> +static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
> +				      *syncobj_timeline)
> +{
> +	syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
> +	syncobj_timeline->timeline = 0;
> +	syncobj_timeline->signal_point = 0;
> +	init_waitqueue_head(&syncobj_timeline->wq);
> +
> +	syncobj_timeline->wait_pt_tree = RB_ROOT;
> +	INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
> +}
> +
>  /**
>   * drm_syncobj_create - create a new syncobj
>   * @out_syncobj: returned syncobj
> @@ -290,6 +621,12 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
>  	kref_init(&syncobj->refcount);
>  	INIT_LIST_HEAD(&syncobj->cb_list);
>  	spin_lock_init(&syncobj->lock);
> +	if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) {
> +		syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
> +		drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
> +	} else {
> +		syncobj->type = DRM_SYNCOBJ_TYPE_NORMAL;
> +	}
>  
>  	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
>  		ret = drm_syncobj_assign_null_handle(syncobj);
> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
> index 335ec501001a..342b3ced3e56 100644
> --- a/include/drm/drm_syncobj.h
> +++ b/include/drm/drm_syncobj.h
> @@ -30,6 +30,25 @@
>  
>  struct drm_syncobj_cb;
>  
> +enum drm_syncobj_type {
> +	DRM_SYNCOBJ_TYPE_NORMAL,
> +	DRM_SYNCOBJ_TYPE_TIMELINE
> +};
> +
> +struct drm_syncobj_timeline {
> +	wait_queue_head_t	wq;
> +	u64 timeline_context;
> +	/**
> +	 * @timeline: syncobj timeline
> +	 */
> +	u64 timeline;
> +	u64 signal_point;
> +
> +
> +	struct rb_root wait_pt_tree;
> +	struct list_head signal_pt_list;
> +};
> +
>  /**
>   * struct drm_syncobj - sync object.
>   *
> @@ -40,6 +59,15 @@ struct drm_syncobj {
>  	 * @refcount: Reference count of this object.
>  	 */
>  	struct kref refcount;
> +	/**
> +	 * @type: indicate syncobj type
> +	 */
> +	enum drm_syncobj_type type;
> +	/**
> +	 * @syncobj_timeline: timeline
> +	 */
> +	struct drm_syncobj_timeline syncobj_timeline;
> +
>  	/**
>  	 * @fence:
>  	 * NULL or a pointer to the fence bound to this object.
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 300f336633f2..cebdb2541eb7 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -717,6 +717,7 @@ struct drm_prime_handle {
>  struct drm_syncobj_create {
>  	__u32 handle;
>  #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
> +#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
>  	__u32 flags;
>  };
>  
> -- 
> 2.14.1
>
Am 23.08.2018 um 10:25 schrieb Chunming Zhou:
> VK_KHR_timeline_semaphore:
> This extension introduces a new type of semaphore that has an integer payload
> identifying a point in a timeline. Such timeline semaphores support the
> following operations:
>     * Host query - A host operation that allows querying the payload of the
>       timeline semaphore.
>     * Host wait - A host operation that allows a blocking wait for a
>       timeline semaphore to reach a specified value.

I think I have a idea what "Host" means in this context, but it would 
probably be better to describe it.

>     * Device wait - A device operation that allows waiting for a
>       timeline semaphore to reach a specified value.
>     * Device signal - A device operation that allows advancing the
>       timeline semaphore to a specified value.
>
> Since it's a timeline, that means the front time point(PT) always is signaled before the late PT.
> a. signal PT design:
> Signal PT fence N depends on PT[N-1] fence and signal opertion fence, when PT[N] fence is signaled,
> the timeline will increase to value of PT[N].
> b. wait PT design:
> Wait PT fence is signaled by reaching timeline point value, when timeline is increasing, will compare
> wait PTs value with new timeline value, if PT value is lower than timeline value, then wait PT will be
> signaled, otherwise keep in list. semaphore wait operation can wait on any point of timeline,
> so need a RB tree to order them. And wait PT could ahead of signal PT, we need a sumission fence to
> perform that.
>
> v2:
> 1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
> 2. move unexposed denitions to .c file. (Daniel Vetter)
> 3. split up the change to drm_syncobj_find_fence() in a separate patch. (Christian)
> 4. split up the change to drm_syncobj_replace_fence() in a separate patch.
> 5. drop the submission_fence implementation and instead use wait_event() for that. (Christian)
> 6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)

I really liked Daniels idea to handle the classic syncobj like a 
timeline synobj with just 1 entry. That can probably simplify the 
implementation quite a bit.

Additional to that an amdgpu patch which shows how the interface is to 
be used is probably something Daniel will want to see as well.

Christian.

>
> TODO:
> 1. CPU query and wait on timeline semaphore.
> 2. test application (Daniel Vetter)
>
> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
> Cc: Christian Konig <christian.koenig@amd.com>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: Daniel Rakos <Daniel.Rakos@amd.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> ---
>   drivers/gpu/drm/drm_syncobj.c | 383 +++++++++++++++++++++++++++++++++++++++---
>   include/drm/drm_syncobj.h     |  28 +++
>   include/uapi/drm/drm.h        |   1 +
>   3 files changed, 389 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index 6227df2cc0a4..f738d78edf65 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -56,6 +56,44 @@
>   #include "drm_internal.h"
>   #include <drm/drm_syncobj.h>
>   
> +struct drm_syncobj_stub_fence {
> +	struct dma_fence base;
> +	spinlock_t lock;
> +};
> +
> +static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
> +{
> +        return "syncobjstub";
> +}
> +
> +static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
> +{
> +    return !dma_fence_is_signaled(fence);
> +}
> +
> +static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
> +	.get_driver_name = drm_syncobj_stub_fence_get_name,
> +	.get_timeline_name = drm_syncobj_stub_fence_get_name,
> +	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
> +	.release = NULL,
> +};
> +
> +struct drm_syncobj_wait_pt {
> +	struct drm_syncobj_stub_fence base;
> +	u64    value;
> +	struct rb_node   node;
> +};
> +struct drm_syncobj_signal_pt {
> +	struct drm_syncobj_stub_fence base;
> +	struct dma_fence *signal_fence;
> +	struct dma_fence *pre_pt_base;
> +	struct dma_fence_cb signal_cb;
> +	struct dma_fence_cb pre_pt_cb;
> +	struct drm_syncobj *syncobj;
> +	u64    value;
> +	struct list_head list;
> +};
> +
>   /**
>    * drm_syncobj_find - lookup and reference a sync object.
>    * @file_private: drm file private pointer
> @@ -137,6 +175,150 @@ void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
>   	spin_unlock(&syncobj->lock);
>   }
>   
> +static void drm_syncobj_timeline_signal_wait_pts(struct drm_syncobj *syncobj)
> +{
> +	struct rb_node *node = NULL;
> +	struct drm_syncobj_wait_pt *wait_pt = NULL;
> +
> +	spin_lock(&syncobj->lock);
> +	for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
> +	    node != NULL; ) {
> +		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
> +		node = rb_next(node);
> +		if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
> +			dma_fence_signal(&wait_pt->base.base);
> +			rb_erase(&wait_pt->node,
> +				 &syncobj->syncobj_timeline.wait_pt_tree);
> +			RB_CLEAR_NODE(&wait_pt->node);
> +			/* kfree(wait_pt) is excuted by fence put */
> +			dma_fence_put(&wait_pt->base.base);
> +		} else {
> +			/* the loop is from left to right, the later entry value is
> +			 * bigger, so don't need to check any more */
> +			break;
> +		}
> +	}
> +	spin_unlock(&syncobj->lock);
> +}
> +
> +
> +static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
> +{
> +	struct dma_fence *fence = NULL;
> +	struct drm_syncobj *syncobj;
> +
> +	fence = signal_pt->signal_fence;
> +	signal_pt->signal_fence = NULL;
> +	dma_fence_put(fence);
> +	fence = signal_pt->pre_pt_base;
> +	signal_pt->pre_pt_base = NULL;
> +	dma_fence_put(fence);
> +
> +	syncobj = signal_pt->syncobj;
> +	spin_lock(&syncobj->lock);
> +	list_del(&signal_pt->list);
> +	syncobj->syncobj_timeline.timeline = signal_pt->value;
> +	spin_unlock(&syncobj->lock);
> +	/* kfree(signal_pt) will be  executed by below fence put */
> +	dma_fence_put(&signal_pt->base.base);
> +	drm_syncobj_timeline_signal_wait_pts(syncobj);
> +}
> +static void pt_signal_fence_func(struct dma_fence *fence,
> +				 struct dma_fence_cb *cb)
> +{
> +	struct drm_syncobj_signal_pt *signal_pt =
> +		container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
> +
> +	if (signal_pt->pre_pt_base &&
> +	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
> +		return;
> +
> +	pt_fence_cb(signal_pt);
> +}
> +static void pt_pre_fence_func(struct dma_fence *fence,
> +				 struct dma_fence_cb *cb)
> +{
> +	struct drm_syncobj_signal_pt *signal_pt =
> +		container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
> +
> +	if (signal_pt->signal_fence &&
> +	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
> +		return;
> +
> +	pt_fence_cb(signal_pt);
> +}
> +
> +static int drm_syncobj_timeline_replace_fence(struct drm_syncobj *syncobj,
> +					      struct dma_fence *fence,
> +					      u64 point)
> +{
> +	struct drm_syncobj_signal_pt *signal_pt =
> +		kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
> +	struct drm_syncobj_signal_pt *tail_pt;
> +	struct dma_fence *tail_pt_fence = NULL;
> +	int ret = 0;
> +
> +	if (!signal_pt)
> +		return -ENOMEM;
> +	if (syncobj->syncobj_timeline.signal_point >= point) {
> +		DRM_WARN("A later signal is ready!");
> +		goto out;
> +	}
> +	if (fence)
> +		dma_fence_get(fence);
> +	spin_lock(&syncobj->lock);
> +	spin_lock_init(&signal_pt->base.lock);
> +	dma_fence_init(&signal_pt->base.base,
> +		       &drm_syncobj_stub_fence_ops,
> +		       &signal_pt->base.lock,
> +		       syncobj->syncobj_timeline.timeline_context, point);
> +	signal_pt->signal_fence =
> +		rcu_dereference_protected(fence,
> +					  lockdep_is_held(&fence->lock));
> +	if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
> +		tail_pt = list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
> +					  struct drm_syncobj_signal_pt, list);
> +		tail_pt_fence = &tail_pt->base.base;
> +		if (dma_fence_is_signaled(tail_pt_fence))
> +			tail_pt_fence = NULL;
> +	}
> +	if (tail_pt_fence)
> +		signal_pt->pre_pt_base =
> +			dma_fence_get(rcu_dereference_protected(tail_pt_fence,
> +								lockdep_is_held(&tail_pt_fence->lock)));
> +
> +	signal_pt->value = point;
> +	syncobj->syncobj_timeline.signal_point = point;
> +	signal_pt->syncobj = syncobj;
> +	INIT_LIST_HEAD(&signal_pt->list);
> +	list_add_tail(&signal_pt->list, &syncobj->syncobj_timeline.signal_pt_list);
> +	spin_unlock(&syncobj->lock);
> +	wake_up_all(&syncobj->syncobj_timeline.wq);
> +	/**
> +	 * Every pt is depending on signal fence and previous pt fence, add
> +	 * callbacks to them
> +	 */
> +	if (!dma_fence_is_signaled(signal_pt->signal_fence))
> +		dma_fence_add_callback(signal_pt->signal_fence,
> +				       &signal_pt->signal_cb,
> +				       pt_signal_fence_func);
> +	else
> +		pt_signal_fence_func(signal_pt->signal_fence,
> +				     &signal_pt->signal_cb);
> +	if (signal_pt->pre_pt_base && !dma_fence_is_signaled(signal_pt->pre_pt_base))
> +		dma_fence_add_callback(signal_pt->pre_pt_base,
> +				       &signal_pt->pre_pt_cb,
> +				       pt_pre_fence_func);
> +	else
> +		pt_pre_fence_func(signal_pt->pre_pt_base, &signal_pt->pre_pt_cb);
> +
> +
> +	return 0;
> +out:
> +	kfree(signal_pt);
> +	return ret;
> +}
> +
>   /**
>    * drm_syncobj_replace_fence - replace fence in a sync object.
>    * @syncobj: Sync object to replace fence in
> @@ -152,6 +334,11 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>   	struct dma_fence *old_fence;
>   	struct drm_syncobj_cb *cur, *tmp;
>   
> +	if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
> +		drm_syncobj_timeline_replace_fence(syncobj, fence,
> +						   point);
> +		return;
> +	}
>   	if (fence)
>   		dma_fence_get(fence);
>   
> @@ -174,28 +361,6 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>   }
>   EXPORT_SYMBOL(drm_syncobj_replace_fence);
>   
> -struct drm_syncobj_stub_fence {
> -	struct dma_fence base;
> -	spinlock_t lock;
> -};
> -
> -static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
> -{
> -        return "syncobjstub";
> -}
> -
> -static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
> -{
> -    return !dma_fence_is_signaled(fence);
> -}
> -
> -static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
> -	.get_driver_name = drm_syncobj_stub_fence_get_name,
> -	.get_timeline_name = drm_syncobj_stub_fence_get_name,
> -	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
> -	.release = NULL,
> -};
> -
>   static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>   {
>   	struct drm_syncobj_stub_fence *fence;
> @@ -215,6 +380,121 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>   	return 0;
>   }
>   
> +static struct drm_syncobj_wait_pt *
> +drm_syncobj_timeline_lookup_wait_pt(struct drm_syncobj *syncobj, u64 point)
> +{
> +    struct rb_node *node = syncobj->syncobj_timeline.wait_pt_tree.rb_node;
> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
> +
> +
> +    spin_lock(&syncobj->lock);
> +    while(node) {
> +	    int result = point - wait_pt->value;
> +
> +	    wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
> +	    if (result < 0)
> +		    node = node->rb_left;
> +	    else if (result > 0)
> +		    node = node->rb_right;
> +	    else
> +		    break;
> +    }
> +    spin_unlock(&syncobj->lock);
> +
> +    return wait_pt;
> +}
> +
> +static struct drm_syncobj_wait_pt *
> +drm_syncobj_timeline_create_wait_pt(struct drm_syncobj *syncobj, u64 point)
> +{
> +	struct drm_syncobj_wait_pt *wait_pt;
> +	struct rb_node **new = &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
> +
> +	wait_pt = kzalloc(sizeof(*wait_pt), GFP_KERNEL);
> +	if (!wait_pt)
> +		return NULL;
> +	spin_lock_init(&wait_pt->base.lock);
> +	dma_fence_init(&wait_pt->base.base,
> +		       &drm_syncobj_stub_fence_ops,
> +		       &wait_pt->base.lock,
> +		       syncobj->syncobj_timeline.timeline_context, point);
> +	wait_pt->value = point;
> +
> +	/* wait pt must be in an order, so that we can easily lookup and signal
> +	 * it */
> +	spin_lock(&syncobj->lock);
> +	if (point <= syncobj->syncobj_timeline.timeline)
> +		dma_fence_signal(&wait_pt->base.base);
> +	while(*new) {
> +		struct drm_syncobj_wait_pt *this =
> +			rb_entry(*new, struct drm_syncobj_wait_pt, node);
> +		int result = wait_pt->value - this->value;
> +
> +		parent = *new;
> +		if (result < 0)
> +			new = &((*new)->rb_left);
> +		else if (result > 0)
> +			new = &((*new)->rb_right);
> +		else
> +			goto exist;
> +	}
> +
> +	rb_link_node(&wait_pt->node, parent, new);
> +	rb_insert_color(&wait_pt->node, &syncobj->syncobj_timeline.wait_pt_tree);
> +	spin_unlock(&syncobj->lock);
> +	return wait_pt;
> +exist:
> +	spin_unlock(&syncobj->lock);
> +	dma_fence_put(&wait_pt->base.base);
> +	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
> +	return wait_pt;
> +}
> +
> +static struct dma_fence *
> +drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 point, u64 flag)
> +{
> +	struct drm_syncobj_wait_pt *wait_pt;
> +
> +	/* already signaled, simply return a signaled stub fence */
> +	if (point <= syncobj->syncobj_timeline.timeline) {
> +		struct drm_syncobj_stub_fence *fence;
> +
> +		fence = kzalloc(sizeof(*fence), GFP_KERNEL);
> +		if (fence == NULL)
> +			return NULL;
> +
> +		spin_lock_init(&fence->lock);
> +		dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
> +			       &fence->lock, 0, 0);
> +		dma_fence_signal(&fence->base);
> +		return &fence->base;
> +	}
> +
> +	/* check if the wait pt exists */
> +	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
> +	if (!wait_pt) {
> +		/* This is a new wait pt, so create it */
> +		wait_pt = drm_syncobj_timeline_create_wait_pt(syncobj, point);
> +		if (!wait_pt)
> +			return NULL;
> +	}
> +	if (wait_pt) {
> +		struct dma_fence *fence;
> +		int ret =
> +			wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
> +				wait_pt->value <= syncobj->syncobj_timeline.signal_point,
> +				msecs_to_jiffies(10000)); /* wait 10s */
> +
> +		if (ret <= 0)
> +			return NULL;
> +		rcu_read_lock();
> +		fence = dma_fence_get_rcu(&wait_pt->base.base);
> +		rcu_read_unlock();
> +		return fence;
> +	}
> +	return NULL;
> +}
> +
>   /**
>    * drm_syncobj_find_fence - lookup and reference the fence in a sync object
>    * @file_private: drm file private pointer
> @@ -240,7 +520,17 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>   	if (!syncobj)
>   		return -ENOENT;
>   
> -	*fence = drm_syncobj_fence_get(syncobj);
> +	if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
> +		/* NORMAL syncobj doesn't care point value */
> +		WARN_ON(point != 0);
> +		*fence = drm_syncobj_fence_get(syncobj);
> +	} else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
> +		*fence = drm_syncobj_timeline_point_get(syncobj, point,
> +							DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT);
> +	} else {
> +		DRM_ERROR("Don't support this type syncobj\n");
> +		*fence = NULL;
> +	}
>   	if (!*fence) {
>   		ret = -EINVAL;
>   	}
> @@ -249,6 +539,34 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>   }
>   EXPORT_SYMBOL(drm_syncobj_find_fence);
>   
> +static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
> +				      struct drm_syncobj_timeline *syncobj_timeline)
> +{
> +	struct rb_node *node = NULL;
> +	struct drm_syncobj_wait_pt *wait_pt = NULL;
> +	struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
> +
> +	spin_lock(&syncobj->lock);
> +	for(node = rb_first(&syncobj_timeline->wait_pt_tree);
> +	    node != NULL; ) {
> +		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
> +		node = rb_next(node);
> +		rb_erase(&wait_pt->node,
> +			 &syncobj_timeline->wait_pt_tree);
> +		RB_CLEAR_NODE(&wait_pt->node);
> +		/* kfree(wait_pt) is excuted by fence put */
> +		dma_fence_put(&wait_pt->base.base);
> +	}
> +	list_for_each_entry_safe(signal_pt, tmp,
> +				 &syncobj_timeline->signal_pt_list, list) {
> +		list_del(&signal_pt->list);
> +		dma_fence_put(signal_pt->signal_fence);
> +		dma_fence_put(signal_pt->pre_pt_base);
> +		dma_fence_put(&signal_pt->base.base);
> +	}
> +	spin_unlock(&syncobj->lock);
> +}
> +
>   /**
>    * drm_syncobj_free - free a sync object.
>    * @kref: kref to free.
> @@ -261,10 +579,23 @@ void drm_syncobj_free(struct kref *kref)
>   						   struct drm_syncobj,
>   						   refcount);
>   	drm_syncobj_replace_fence(syncobj, NULL, 0);
> +	drm_syncobj_timeline_fini(syncobj, &syncobj->syncobj_timeline);
>   	kfree(syncobj);
>   }
>   EXPORT_SYMBOL(drm_syncobj_free);
>   
> +static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
> +				      *syncobj_timeline)
> +{
> +	syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
> +	syncobj_timeline->timeline = 0;
> +	syncobj_timeline->signal_point = 0;
> +	init_waitqueue_head(&syncobj_timeline->wq);
> +
> +	syncobj_timeline->wait_pt_tree = RB_ROOT;
> +	INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
> +}
> +
>   /**
>    * drm_syncobj_create - create a new syncobj
>    * @out_syncobj: returned syncobj
> @@ -290,6 +621,12 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
>   	kref_init(&syncobj->refcount);
>   	INIT_LIST_HEAD(&syncobj->cb_list);
>   	spin_lock_init(&syncobj->lock);
> +	if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) {
> +		syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
> +		drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
> +	} else {
> +		syncobj->type = DRM_SYNCOBJ_TYPE_NORMAL;
> +	}
>   
>   	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
>   		ret = drm_syncobj_assign_null_handle(syncobj);
> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
> index 335ec501001a..342b3ced3e56 100644
> --- a/include/drm/drm_syncobj.h
> +++ b/include/drm/drm_syncobj.h
> @@ -30,6 +30,25 @@
>   
>   struct drm_syncobj_cb;
>   
> +enum drm_syncobj_type {
> +	DRM_SYNCOBJ_TYPE_NORMAL,
> +	DRM_SYNCOBJ_TYPE_TIMELINE
> +};
> +
> +struct drm_syncobj_timeline {
> +	wait_queue_head_t	wq;
> +	u64 timeline_context;
> +	/**
> +	 * @timeline: syncobj timeline
> +	 */
> +	u64 timeline;
> +	u64 signal_point;
> +
> +
> +	struct rb_root wait_pt_tree;
> +	struct list_head signal_pt_list;
> +};
> +
>   /**
>    * struct drm_syncobj - sync object.
>    *
> @@ -40,6 +59,15 @@ struct drm_syncobj {
>   	 * @refcount: Reference count of this object.
>   	 */
>   	struct kref refcount;
> +	/**
> +	 * @type: indicate syncobj type
> +	 */
> +	enum drm_syncobj_type type;
> +	/**
> +	 * @syncobj_timeline: timeline
> +	 */
> +	struct drm_syncobj_timeline syncobj_timeline;
> +
>   	/**
>   	 * @fence:
>   	 * NULL or a pointer to the fence bound to this object.
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 300f336633f2..cebdb2541eb7 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -717,6 +717,7 @@ struct drm_prime_handle {
>   struct drm_syncobj_create {
>   	__u32 handle;
>   #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
> +#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
>   	__u32 flags;
>   };
>
On 2018年08月23日 17:08, Daniel Vetter wrote:
> On Thu, Aug 23, 2018 at 04:25:42PM +0800, Chunming Zhou wrote:
>> VK_KHR_timeline_semaphore:
>> This extension introduces a new type of semaphore that has an integer payload
>> identifying a point in a timeline. Such timeline semaphores support the
>> following operations:
>>     * Host query - A host operation that allows querying the payload of the
>>       timeline semaphore.
>>     * Host wait - A host operation that allows a blocking wait for a
>>       timeline semaphore to reach a specified value.
>>     * Device wait - A device operation that allows waiting for a
>>       timeline semaphore to reach a specified value.
>>     * Device signal - A device operation that allows advancing the
>>       timeline semaphore to a specified value.
>>
>> Since it's a timeline, that means the front time point(PT) always is signaled before the late PT.
>> a. signal PT design:
>> Signal PT fence N depends on PT[N-1] fence and signal opertion fence, when PT[N] fence is signaled,
>> the timeline will increase to value of PT[N].
>> b. wait PT design:
>> Wait PT fence is signaled by reaching timeline point value, when timeline is increasing, will compare
>> wait PTs value with new timeline value, if PT value is lower than timeline value, then wait PT will be
>> signaled, otherwise keep in list. semaphore wait operation can wait on any point of timeline,
>> so need a RB tree to order them. And wait PT could ahead of signal PT, we need a sumission fence to
>> perform that.
>>
>> v2:
>> 1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
>> 2. move unexposed denitions to .c file. (Daniel Vetter)
>> 3. split up the change to drm_syncobj_find_fence() in a separate patch. (Christian)
>> 4. split up the change to drm_syncobj_replace_fence() in a separate patch.
>> 5. drop the submission_fence implementation and instead use wait_event() for that. (Christian)
>> 6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)
> Depending upon how it's going to be used, this is the wrong thing to do.
>
>> TODO:
>> 1. CPU query and wait on timeline semaphore.
>> 2. test application (Daniel Vetter)
> I also had some more suggestions, around aligning the two concepts of
> future fences
submission fence is replaced by wait_event, so I don't address your 
future fence suggestion. And welcome to explain future fence status.
> and at least trying to merge the timeline and the other
> fence (which really is just a special case of a timeline with only 1
> slot).
Could you detail that? Do you mean merge syncobj->fence to timeline point?

Thanks,
David Zhou
> -Daniel
>
>> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
>> Cc: Christian Konig <christian.koenig@amd.com>
>> Cc: Dave Airlie <airlied@redhat.com>
>> Cc: Daniel Rakos <Daniel.Rakos@amd.com>
>> Cc: Daniel Vetter <daniel@ffwll.ch>
>> ---
>>   drivers/gpu/drm/drm_syncobj.c | 383 +++++++++++++++++++++++++++++++++++++++---
>>   include/drm/drm_syncobj.h     |  28 +++
>>   include/uapi/drm/drm.h        |   1 +
>>   3 files changed, 389 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
>> index 6227df2cc0a4..f738d78edf65 100644
>> --- a/drivers/gpu/drm/drm_syncobj.c
>> +++ b/drivers/gpu/drm/drm_syncobj.c
>> @@ -56,6 +56,44 @@
>>   #include "drm_internal.h"
>>   #include <drm/drm_syncobj.h>
>>   
>> +struct drm_syncobj_stub_fence {
>> +	struct dma_fence base;
>> +	spinlock_t lock;
>> +};
>> +
>> +static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
>> +{
>> +        return "syncobjstub";
>> +}
>> +
>> +static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
>> +{
>> +    return !dma_fence_is_signaled(fence);
>> +}
>> +
>> +static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>> +	.get_driver_name = drm_syncobj_stub_fence_get_name,
>> +	.get_timeline_name = drm_syncobj_stub_fence_get_name,
>> +	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>> +	.release = NULL,
>> +};
>> +
>> +struct drm_syncobj_wait_pt {
>> +	struct drm_syncobj_stub_fence base;
>> +	u64    value;
>> +	struct rb_node   node;
>> +};
>> +struct drm_syncobj_signal_pt {
>> +	struct drm_syncobj_stub_fence base;
>> +	struct dma_fence *signal_fence;
>> +	struct dma_fence *pre_pt_base;
>> +	struct dma_fence_cb signal_cb;
>> +	struct dma_fence_cb pre_pt_cb;
>> +	struct drm_syncobj *syncobj;
>> +	u64    value;
>> +	struct list_head list;
>> +};
>> +
>>   /**
>>    * drm_syncobj_find - lookup and reference a sync object.
>>    * @file_private: drm file private pointer
>> @@ -137,6 +175,150 @@ void drm_syncobj_remove_callback(struct drm_syncobj *syncobj,
>>   	spin_unlock(&syncobj->lock);
>>   }
>>   
>> +static void drm_syncobj_timeline_signal_wait_pts(struct drm_syncobj *syncobj)
>> +{
>> +	struct rb_node *node = NULL;
>> +	struct drm_syncobj_wait_pt *wait_pt = NULL;
>> +
>> +	spin_lock(&syncobj->lock);
>> +	for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
>> +	    node != NULL; ) {
>> +		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>> +		node = rb_next(node);
>> +		if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
>> +			dma_fence_signal(&wait_pt->base.base);
>> +			rb_erase(&wait_pt->node,
>> +				 &syncobj->syncobj_timeline.wait_pt_tree);
>> +			RB_CLEAR_NODE(&wait_pt->node);
>> +			/* kfree(wait_pt) is excuted by fence put */
>> +			dma_fence_put(&wait_pt->base.base);
>> +		} else {
>> +			/* the loop is from left to right, the later entry value is
>> +			 * bigger, so don't need to check any more */
>> +			break;
>> +		}
>> +	}
>> +	spin_unlock(&syncobj->lock);
>> +}
>> +
>> +
>> +static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
>> +{
>> +	struct dma_fence *fence = NULL;
>> +	struct drm_syncobj *syncobj;
>> +
>> +	fence = signal_pt->signal_fence;
>> +	signal_pt->signal_fence = NULL;
>> +	dma_fence_put(fence);
>> +	fence = signal_pt->pre_pt_base;
>> +	signal_pt->pre_pt_base = NULL;
>> +	dma_fence_put(fence);
>> +
>> +	syncobj = signal_pt->syncobj;
>> +	spin_lock(&syncobj->lock);
>> +	list_del(&signal_pt->list);
>> +	syncobj->syncobj_timeline.timeline = signal_pt->value;
>> +	spin_unlock(&syncobj->lock);
>> +	/* kfree(signal_pt) will be  executed by below fence put */
>> +	dma_fence_put(&signal_pt->base.base);
>> +	drm_syncobj_timeline_signal_wait_pts(syncobj);
>> +}
>> +static void pt_signal_fence_func(struct dma_fence *fence,
>> +				 struct dma_fence_cb *cb)
>> +{
>> +	struct drm_syncobj_signal_pt *signal_pt =
>> +		container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
>> +
>> +	if (signal_pt->pre_pt_base &&
>> +	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
>> +		return;
>> +
>> +	pt_fence_cb(signal_pt);
>> +}
>> +static void pt_pre_fence_func(struct dma_fence *fence,
>> +				 struct dma_fence_cb *cb)
>> +{
>> +	struct drm_syncobj_signal_pt *signal_pt =
>> +		container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
>> +
>> +	if (signal_pt->signal_fence &&
>> +	    !dma_fence_is_signaled(signal_pt->pre_pt_base))
>> +		return;
>> +
>> +	pt_fence_cb(signal_pt);
>> +}
>> +
>> +static int drm_syncobj_timeline_replace_fence(struct drm_syncobj *syncobj,
>> +					      struct dma_fence *fence,
>> +					      u64 point)
>> +{
>> +	struct drm_syncobj_signal_pt *signal_pt =
>> +		kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
>> +	struct drm_syncobj_signal_pt *tail_pt;
>> +	struct dma_fence *tail_pt_fence = NULL;
>> +	int ret = 0;
>> +
>> +	if (!signal_pt)
>> +		return -ENOMEM;
>> +	if (syncobj->syncobj_timeline.signal_point >= point) {
>> +		DRM_WARN("A later signal is ready!");
>> +		goto out;
>> +	}
>> +	if (fence)
>> +		dma_fence_get(fence);
>> +	spin_lock(&syncobj->lock);
>> +	spin_lock_init(&signal_pt->base.lock);
>> +	dma_fence_init(&signal_pt->base.base,
>> +		       &drm_syncobj_stub_fence_ops,
>> +		       &signal_pt->base.lock,
>> +		       syncobj->syncobj_timeline.timeline_context, point);
>> +	signal_pt->signal_fence =
>> +		rcu_dereference_protected(fence,
>> +					  lockdep_is_held(&fence->lock));
>> +	if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
>> +		tail_pt = list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
>> +					  struct drm_syncobj_signal_pt, list);
>> +		tail_pt_fence = &tail_pt->base.base;
>> +		if (dma_fence_is_signaled(tail_pt_fence))
>> +			tail_pt_fence = NULL;
>> +	}
>> +	if (tail_pt_fence)
>> +		signal_pt->pre_pt_base =
>> +			dma_fence_get(rcu_dereference_protected(tail_pt_fence,
>> +								lockdep_is_held(&tail_pt_fence->lock)));
>> +
>> +	signal_pt->value = point;
>> +	syncobj->syncobj_timeline.signal_point = point;
>> +	signal_pt->syncobj = syncobj;
>> +	INIT_LIST_HEAD(&signal_pt->list);
>> +	list_add_tail(&signal_pt->list, &syncobj->syncobj_timeline.signal_pt_list);
>> +	spin_unlock(&syncobj->lock);
>> +	wake_up_all(&syncobj->syncobj_timeline.wq);
>> +	/**
>> +	 * Every pt is depending on signal fence and previous pt fence, add
>> +	 * callbacks to them
>> +	 */
>> +	if (!dma_fence_is_signaled(signal_pt->signal_fence))
>> +		dma_fence_add_callback(signal_pt->signal_fence,
>> +				       &signal_pt->signal_cb,
>> +				       pt_signal_fence_func);
>> +	else
>> +		pt_signal_fence_func(signal_pt->signal_fence,
>> +				     &signal_pt->signal_cb);
>> +	if (signal_pt->pre_pt_base && !dma_fence_is_signaled(signal_pt->pre_pt_base))
>> +		dma_fence_add_callback(signal_pt->pre_pt_base,
>> +				       &signal_pt->pre_pt_cb,
>> +				       pt_pre_fence_func);
>> +	else
>> +		pt_pre_fence_func(signal_pt->pre_pt_base, &signal_pt->pre_pt_cb);
>> +
>> +
>> +	return 0;
>> +out:
>> +	kfree(signal_pt);
>> +	return ret;
>> +}
>> +
>>   /**
>>    * drm_syncobj_replace_fence - replace fence in a sync object.
>>    * @syncobj: Sync object to replace fence in
>> @@ -152,6 +334,11 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>>   	struct dma_fence *old_fence;
>>   	struct drm_syncobj_cb *cur, *tmp;
>>   
>> +	if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>> +		drm_syncobj_timeline_replace_fence(syncobj, fence,
>> +						   point);
>> +		return;
>> +	}
>>   	if (fence)
>>   		dma_fence_get(fence);
>>   
>> @@ -174,28 +361,6 @@ void drm_syncobj_replace_fence(struct drm_syncobj *syncobj,
>>   }
>>   EXPORT_SYMBOL(drm_syncobj_replace_fence);
>>   
>> -struct drm_syncobj_stub_fence {
>> -	struct dma_fence base;
>> -	spinlock_t lock;
>> -};
>> -
>> -static const char *drm_syncobj_stub_fence_get_name(struct dma_fence *fence)
>> -{
>> -        return "syncobjstub";
>> -}
>> -
>> -static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence *fence)
>> -{
>> -    return !dma_fence_is_signaled(fence);
>> -}
>> -
>> -static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>> -	.get_driver_name = drm_syncobj_stub_fence_get_name,
>> -	.get_timeline_name = drm_syncobj_stub_fence_get_name,
>> -	.enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>> -	.release = NULL,
>> -};
>> -
>>   static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>   {
>>   	struct drm_syncobj_stub_fence *fence;
>> @@ -215,6 +380,121 @@ static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>   	return 0;
>>   }
>>   
>> +static struct drm_syncobj_wait_pt *
>> +drm_syncobj_timeline_lookup_wait_pt(struct drm_syncobj *syncobj, u64 point)
>> +{
>> +    struct rb_node *node = syncobj->syncobj_timeline.wait_pt_tree.rb_node;
>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>> +
>> +
>> +    spin_lock(&syncobj->lock);
>> +    while(node) {
>> +	    int result = point - wait_pt->value;
>> +
>> +	    wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>> +	    if (result < 0)
>> +		    node = node->rb_left;
>> +	    else if (result > 0)
>> +		    node = node->rb_right;
>> +	    else
>> +		    break;
>> +    }
>> +    spin_unlock(&syncobj->lock);
>> +
>> +    return wait_pt;
>> +}
>> +
>> +static struct drm_syncobj_wait_pt *
>> +drm_syncobj_timeline_create_wait_pt(struct drm_syncobj *syncobj, u64 point)
>> +{
>> +	struct drm_syncobj_wait_pt *wait_pt;
>> +	struct rb_node **new = &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
>> +
>> +	wait_pt = kzalloc(sizeof(*wait_pt), GFP_KERNEL);
>> +	if (!wait_pt)
>> +		return NULL;
>> +	spin_lock_init(&wait_pt->base.lock);
>> +	dma_fence_init(&wait_pt->base.base,
>> +		       &drm_syncobj_stub_fence_ops,
>> +		       &wait_pt->base.lock,
>> +		       syncobj->syncobj_timeline.timeline_context, point);
>> +	wait_pt->value = point;
>> +
>> +	/* wait pt must be in an order, so that we can easily lookup and signal
>> +	 * it */
>> +	spin_lock(&syncobj->lock);
>> +	if (point <= syncobj->syncobj_timeline.timeline)
>> +		dma_fence_signal(&wait_pt->base.base);
>> +	while(*new) {
>> +		struct drm_syncobj_wait_pt *this =
>> +			rb_entry(*new, struct drm_syncobj_wait_pt, node);
>> +		int result = wait_pt->value - this->value;
>> +
>> +		parent = *new;
>> +		if (result < 0)
>> +			new = &((*new)->rb_left);
>> +		else if (result > 0)
>> +			new = &((*new)->rb_right);
>> +		else
>> +			goto exist;
>> +	}
>> +
>> +	rb_link_node(&wait_pt->node, parent, new);
>> +	rb_insert_color(&wait_pt->node, &syncobj->syncobj_timeline.wait_pt_tree);
>> +	spin_unlock(&syncobj->lock);
>> +	return wait_pt;
>> +exist:
>> +	spin_unlock(&syncobj->lock);
>> +	dma_fence_put(&wait_pt->base.base);
>> +	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
>> +	return wait_pt;
>> +}
>> +
>> +static struct dma_fence *
>> +drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 point, u64 flag)
>> +{
>> +	struct drm_syncobj_wait_pt *wait_pt;
>> +
>> +	/* already signaled, simply return a signaled stub fence */
>> +	if (point <= syncobj->syncobj_timeline.timeline) {
>> +		struct drm_syncobj_stub_fence *fence;
>> +
>> +		fence = kzalloc(sizeof(*fence), GFP_KERNEL);
>> +		if (fence == NULL)
>> +			return NULL;
>> +
>> +		spin_lock_init(&fence->lock);
>> +		dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
>> +			       &fence->lock, 0, 0);
>> +		dma_fence_signal(&fence->base);
>> +		return &fence->base;
>> +	}
>> +
>> +	/* check if the wait pt exists */
>> +	wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
>> +	if (!wait_pt) {
>> +		/* This is a new wait pt, so create it */
>> +		wait_pt = drm_syncobj_timeline_create_wait_pt(syncobj, point);
>> +		if (!wait_pt)
>> +			return NULL;
>> +	}
>> +	if (wait_pt) {
>> +		struct dma_fence *fence;
>> +		int ret =
>> +			wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
>> +				wait_pt->value <= syncobj->syncobj_timeline.signal_point,
>> +				msecs_to_jiffies(10000)); /* wait 10s */
>> +
>> +		if (ret <= 0)
>> +			return NULL;
>> +		rcu_read_lock();
>> +		fence = dma_fence_get_rcu(&wait_pt->base.base);
>> +		rcu_read_unlock();
>> +		return fence;
>> +	}
>> +	return NULL;
>> +}
>> +
>>   /**
>>    * drm_syncobj_find_fence - lookup and reference the fence in a sync object
>>    * @file_private: drm file private pointer
>> @@ -240,7 +520,17 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>>   	if (!syncobj)
>>   		return -ENOENT;
>>   
>> -	*fence = drm_syncobj_fence_get(syncobj);
>> +	if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
>> +		/* NORMAL syncobj doesn't care point value */
>> +		WARN_ON(point != 0);
>> +		*fence = drm_syncobj_fence_get(syncobj);
>> +	} else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>> +		*fence = drm_syncobj_timeline_point_get(syncobj, point,
>> +							DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT);
>> +	} else {
>> +		DRM_ERROR("Don't support this type syncobj\n");
>> +		*fence = NULL;
>> +	}
>>   	if (!*fence) {
>>   		ret = -EINVAL;
>>   	}
>> @@ -249,6 +539,34 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
>>   }
>>   EXPORT_SYMBOL(drm_syncobj_find_fence);
>>   
>> +static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
>> +				      struct drm_syncobj_timeline *syncobj_timeline)
>> +{
>> +	struct rb_node *node = NULL;
>> +	struct drm_syncobj_wait_pt *wait_pt = NULL;
>> +	struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
>> +
>> +	spin_lock(&syncobj->lock);
>> +	for(node = rb_first(&syncobj_timeline->wait_pt_tree);
>> +	    node != NULL; ) {
>> +		wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>> +		node = rb_next(node);
>> +		rb_erase(&wait_pt->node,
>> +			 &syncobj_timeline->wait_pt_tree);
>> +		RB_CLEAR_NODE(&wait_pt->node);
>> +		/* kfree(wait_pt) is excuted by fence put */
>> +		dma_fence_put(&wait_pt->base.base);
>> +	}
>> +	list_for_each_entry_safe(signal_pt, tmp,
>> +				 &syncobj_timeline->signal_pt_list, list) {
>> +		list_del(&signal_pt->list);
>> +		dma_fence_put(signal_pt->signal_fence);
>> +		dma_fence_put(signal_pt->pre_pt_base);
>> +		dma_fence_put(&signal_pt->base.base);
>> +	}
>> +	spin_unlock(&syncobj->lock);
>> +}
>> +
>>   /**
>>    * drm_syncobj_free - free a sync object.
>>    * @kref: kref to free.
>> @@ -261,10 +579,23 @@ void drm_syncobj_free(struct kref *kref)
>>   						   struct drm_syncobj,
>>   						   refcount);
>>   	drm_syncobj_replace_fence(syncobj, NULL, 0);
>> +	drm_syncobj_timeline_fini(syncobj, &syncobj->syncobj_timeline);
>>   	kfree(syncobj);
>>   }
>>   EXPORT_SYMBOL(drm_syncobj_free);
>>   
>> +static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
>> +				      *syncobj_timeline)
>> +{
>> +	syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
>> +	syncobj_timeline->timeline = 0;
>> +	syncobj_timeline->signal_point = 0;
>> +	init_waitqueue_head(&syncobj_timeline->wq);
>> +
>> +	syncobj_timeline->wait_pt_tree = RB_ROOT;
>> +	INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
>> +}
>> +
>>   /**
>>    * drm_syncobj_create - create a new syncobj
>>    * @out_syncobj: returned syncobj
>> @@ -290,6 +621,12 @@ int drm_syncobj_create(struct drm_syncobj **out_syncobj, uint32_t flags,
>>   	kref_init(&syncobj->refcount);
>>   	INIT_LIST_HEAD(&syncobj->cb_list);
>>   	spin_lock_init(&syncobj->lock);
>> +	if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) {
>> +		syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
>> +		drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
>> +	} else {
>> +		syncobj->type = DRM_SYNCOBJ_TYPE_NORMAL;
>> +	}
>>   
>>   	if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
>>   		ret = drm_syncobj_assign_null_handle(syncobj);
>> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
>> index 335ec501001a..342b3ced3e56 100644
>> --- a/include/drm/drm_syncobj.h
>> +++ b/include/drm/drm_syncobj.h
>> @@ -30,6 +30,25 @@
>>   
>>   struct drm_syncobj_cb;
>>   
>> +enum drm_syncobj_type {
>> +	DRM_SYNCOBJ_TYPE_NORMAL,
>> +	DRM_SYNCOBJ_TYPE_TIMELINE
>> +};
>> +
>> +struct drm_syncobj_timeline {
>> +	wait_queue_head_t	wq;
>> +	u64 timeline_context;
>> +	/**
>> +	 * @timeline: syncobj timeline
>> +	 */
>> +	u64 timeline;
>> +	u64 signal_point;
>> +
>> +
>> +	struct rb_root wait_pt_tree;
>> +	struct list_head signal_pt_list;
>> +};
>> +
>>   /**
>>    * struct drm_syncobj - sync object.
>>    *
>> @@ -40,6 +59,15 @@ struct drm_syncobj {
>>   	 * @refcount: Reference count of this object.
>>   	 */
>>   	struct kref refcount;
>> +	/**
>> +	 * @type: indicate syncobj type
>> +	 */
>> +	enum drm_syncobj_type type;
>> +	/**
>> +	 * @syncobj_timeline: timeline
>> +	 */
>> +	struct drm_syncobj_timeline syncobj_timeline;
>> +
>>   	/**
>>   	 * @fence:
>>   	 * NULL or a pointer to the fence bound to this object.
>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>> index 300f336633f2..cebdb2541eb7 100644
>> --- a/include/uapi/drm/drm.h
>> +++ b/include/uapi/drm/drm.h
>> @@ -717,6 +717,7 @@ struct drm_prime_handle {
>>   struct drm_syncobj_create {
>>   	__u32 handle;
>>   #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
>> +#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
>>   	__u32 flags;
>>   };
>>   
>> -- 
>> 2.14.1
>>
On 2018年08月23日 17:15, Christian König wrote:
> Am 23.08.2018 um 10:25 schrieb Chunming Zhou:
>> VK_KHR_timeline_semaphore:
>> This extension introduces a new type of semaphore that has an integer 
>> payload
>> identifying a point in a timeline. Such timeline semaphores support the
>> following operations:
>>     * Host query - A host operation that allows querying the payload 
>> of the
>>       timeline semaphore.
>>     * Host wait - A host operation that allows a blocking wait for a
>>       timeline semaphore to reach a specified value.
>
> I think I have a idea what "Host" means in this context, but it would 
> probably be better to describe it.

How about "CPU"?

>>     * Device wait - A device operation that allows waiting for a
>>       timeline semaphore to reach a specified value.
>>     * Device signal - A device operation that allows advancing the
>>       timeline semaphore to a specified value.
>>
>> Since it's a timeline, that means the front time point(PT) always is 
>> signaled before the late PT.
>> a. signal PT design:
>> Signal PT fence N depends on PT[N-1] fence and signal opertion fence, 
>> when PT[N] fence is signaled,
>> the timeline will increase to value of PT[N].
>> b. wait PT design:
>> Wait PT fence is signaled by reaching timeline point value, when 
>> timeline is increasing, will compare
>> wait PTs value with new timeline value, if PT value is lower than 
>> timeline value, then wait PT will be
>> signaled, otherwise keep in list. semaphore wait operation can wait 
>> on any point of timeline,
>> so need a RB tree to order them. And wait PT could ahead of signal 
>> PT, we need a sumission fence to
>> perform that.
>>
>> v2:
>> 1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
>> 2. move unexposed denitions to .c file. (Daniel Vetter)
>> 3. split up the change to drm_syncobj_find_fence() in a separate 
>> patch. (Christian)
>> 4. split up the change to drm_syncobj_replace_fence() in a separate 
>> patch.
>> 5. drop the submission_fence implementation and instead use 
>> wait_event() for that. (Christian)
>> 6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)
>
> I really liked Daniels idea to handle the classic syncobj like a 
> timeline synobj with just 1 entry. That can probably simplify the 
> implementation quite a bit.
Yeah, after timeline, seems we can remove old syncobj->fence, right? 
will try to unify them in additional patch.

Thanks,
David Zhou
>
> Additional to that an amdgpu patch which shows how the interface is to 
> be used is probably something Daniel will want to see as well.
>
> Christian.
>
>>
>> TODO:
>> 1. CPU query and wait on timeline semaphore.
>> 2. test application (Daniel Vetter)
>>
>> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
>> Cc: Christian Konig <christian.koenig@amd.com>
>> Cc: Dave Airlie <airlied@redhat.com>
>> Cc: Daniel Rakos <Daniel.Rakos@amd.com>
>> Cc: Daniel Vetter <daniel@ffwll.ch>
>> ---
>>   drivers/gpu/drm/drm_syncobj.c | 383 
>> +++++++++++++++++++++++++++++++++++++++---
>>   include/drm/drm_syncobj.h     |  28 +++
>>   include/uapi/drm/drm.h        |   1 +
>>   3 files changed, 389 insertions(+), 23 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_syncobj.c 
>> b/drivers/gpu/drm/drm_syncobj.c
>> index 6227df2cc0a4..f738d78edf65 100644
>> --- a/drivers/gpu/drm/drm_syncobj.c
>> +++ b/drivers/gpu/drm/drm_syncobj.c
>> @@ -56,6 +56,44 @@
>>   #include "drm_internal.h"
>>   #include <drm/drm_syncobj.h>
>>   +struct drm_syncobj_stub_fence {
>> +    struct dma_fence base;
>> +    spinlock_t lock;
>> +};
>> +
>> +static const char *drm_syncobj_stub_fence_get_name(struct dma_fence 
>> *fence)
>> +{
>> +        return "syncobjstub";
>> +}
>> +
>> +static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence 
>> *fence)
>> +{
>> +    return !dma_fence_is_signaled(fence);
>> +}
>> +
>> +static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>> +    .get_driver_name = drm_syncobj_stub_fence_get_name,
>> +    .get_timeline_name = drm_syncobj_stub_fence_get_name,
>> +    .enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>> +    .release = NULL,
>> +};
>> +
>> +struct drm_syncobj_wait_pt {
>> +    struct drm_syncobj_stub_fence base;
>> +    u64    value;
>> +    struct rb_node   node;
>> +};
>> +struct drm_syncobj_signal_pt {
>> +    struct drm_syncobj_stub_fence base;
>> +    struct dma_fence *signal_fence;
>> +    struct dma_fence *pre_pt_base;
>> +    struct dma_fence_cb signal_cb;
>> +    struct dma_fence_cb pre_pt_cb;
>> +    struct drm_syncobj *syncobj;
>> +    u64    value;
>> +    struct list_head list;
>> +};
>> +
>>   /**
>>    * drm_syncobj_find - lookup and reference a sync object.
>>    * @file_private: drm file private pointer
>> @@ -137,6 +175,150 @@ void drm_syncobj_remove_callback(struct 
>> drm_syncobj *syncobj,
>>       spin_unlock(&syncobj->lock);
>>   }
>>   +static void drm_syncobj_timeline_signal_wait_pts(struct 
>> drm_syncobj *syncobj)
>> +{
>> +    struct rb_node *node = NULL;
>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>> +
>> +    spin_lock(&syncobj->lock);
>> +    for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
>> +        node != NULL; ) {
>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>> +        node = rb_next(node);
>> +        if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
>> +            dma_fence_signal(&wait_pt->base.base);
>> +            rb_erase(&wait_pt->node,
>> + &syncobj->syncobj_timeline.wait_pt_tree);
>> +            RB_CLEAR_NODE(&wait_pt->node);
>> +            /* kfree(wait_pt) is excuted by fence put */
>> +            dma_fence_put(&wait_pt->base.base);
>> +        } else {
>> +            /* the loop is from left to right, the later entry value is
>> +             * bigger, so don't need to check any more */
>> +            break;
>> +        }
>> +    }
>> +    spin_unlock(&syncobj->lock);
>> +}
>> +
>> +
>> +static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
>> +{
>> +    struct dma_fence *fence = NULL;
>> +    struct drm_syncobj *syncobj;
>> +
>> +    fence = signal_pt->signal_fence;
>> +    signal_pt->signal_fence = NULL;
>> +    dma_fence_put(fence);
>> +    fence = signal_pt->pre_pt_base;
>> +    signal_pt->pre_pt_base = NULL;
>> +    dma_fence_put(fence);
>> +
>> +    syncobj = signal_pt->syncobj;
>> +    spin_lock(&syncobj->lock);
>> +    list_del(&signal_pt->list);
>> +    syncobj->syncobj_timeline.timeline = signal_pt->value;
>> +    spin_unlock(&syncobj->lock);
>> +    /* kfree(signal_pt) will be  executed by below fence put */
>> +    dma_fence_put(&signal_pt->base.base);
>> +    drm_syncobj_timeline_signal_wait_pts(syncobj);
>> +}
>> +static void pt_signal_fence_func(struct dma_fence *fence,
>> +                 struct dma_fence_cb *cb)
>> +{
>> +    struct drm_syncobj_signal_pt *signal_pt =
>> +        container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
>> +
>> +    if (signal_pt->pre_pt_base &&
>> +        !dma_fence_is_signaled(signal_pt->pre_pt_base))
>> +        return;
>> +
>> +    pt_fence_cb(signal_pt);
>> +}
>> +static void pt_pre_fence_func(struct dma_fence *fence,
>> +                 struct dma_fence_cb *cb)
>> +{
>> +    struct drm_syncobj_signal_pt *signal_pt =
>> +        container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
>> +
>> +    if (signal_pt->signal_fence &&
>> +        !dma_fence_is_signaled(signal_pt->pre_pt_base))
>> +        return;
>> +
>> +    pt_fence_cb(signal_pt);
>> +}
>> +
>> +static int drm_syncobj_timeline_replace_fence(struct drm_syncobj 
>> *syncobj,
>> +                          struct dma_fence *fence,
>> +                          u64 point)
>> +{
>> +    struct drm_syncobj_signal_pt *signal_pt =
>> +        kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
>> +    struct drm_syncobj_signal_pt *tail_pt;
>> +    struct dma_fence *tail_pt_fence = NULL;
>> +    int ret = 0;
>> +
>> +    if (!signal_pt)
>> +        return -ENOMEM;
>> +    if (syncobj->syncobj_timeline.signal_point >= point) {
>> +        DRM_WARN("A later signal is ready!");
>> +        goto out;
>> +    }
>> +    if (fence)
>> +        dma_fence_get(fence);
>> +    spin_lock(&syncobj->lock);
>> +    spin_lock_init(&signal_pt->base.lock);
>> +    dma_fence_init(&signal_pt->base.base,
>> +               &drm_syncobj_stub_fence_ops,
>> +               &signal_pt->base.lock,
>> +               syncobj->syncobj_timeline.timeline_context, point);
>> +    signal_pt->signal_fence =
>> +        rcu_dereference_protected(fence,
>> +                      lockdep_is_held(&fence->lock));
>> +    if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
>> +        tail_pt = 
>> list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
>> +                      struct drm_syncobj_signal_pt, list);
>> +        tail_pt_fence = &tail_pt->base.base;
>> +        if (dma_fence_is_signaled(tail_pt_fence))
>> +            tail_pt_fence = NULL;
>> +    }
>> +    if (tail_pt_fence)
>> +        signal_pt->pre_pt_base =
>> + dma_fence_get(rcu_dereference_protected(tail_pt_fence,
>> + lockdep_is_held(&tail_pt_fence->lock)));
>> +
>> +    signal_pt->value = point;
>> +    syncobj->syncobj_timeline.signal_point = point;
>> +    signal_pt->syncobj = syncobj;
>> +    INIT_LIST_HEAD(&signal_pt->list);
>> +    list_add_tail(&signal_pt->list, 
>> &syncobj->syncobj_timeline.signal_pt_list);
>> +    spin_unlock(&syncobj->lock);
>> +    wake_up_all(&syncobj->syncobj_timeline.wq);
>> +    /**
>> +     * Every pt is depending on signal fence and previous pt fence, add
>> +     * callbacks to them
>> +     */
>> +    if (!dma_fence_is_signaled(signal_pt->signal_fence))
>> +        dma_fence_add_callback(signal_pt->signal_fence,
>> +                       &signal_pt->signal_cb,
>> +                       pt_signal_fence_func);
>> +    else
>> +        pt_signal_fence_func(signal_pt->signal_fence,
>> +                     &signal_pt->signal_cb);
>> +    if (signal_pt->pre_pt_base && 
>> !dma_fence_is_signaled(signal_pt->pre_pt_base))
>> +        dma_fence_add_callback(signal_pt->pre_pt_base,
>> +                       &signal_pt->pre_pt_cb,
>> +                       pt_pre_fence_func);
>> +    else
>> +        pt_pre_fence_func(signal_pt->pre_pt_base, 
>> &signal_pt->pre_pt_cb);
>> +
>> +
>> +    return 0;
>> +out:
>> +    kfree(signal_pt);
>> +    return ret;
>> +}
>> +
>>   /**
>>    * drm_syncobj_replace_fence - replace fence in a sync object.
>>    * @syncobj: Sync object to replace fence in
>> @@ -152,6 +334,11 @@ void drm_syncobj_replace_fence(struct 
>> drm_syncobj *syncobj,
>>       struct dma_fence *old_fence;
>>       struct drm_syncobj_cb *cur, *tmp;
>>   +    if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>> +        drm_syncobj_timeline_replace_fence(syncobj, fence,
>> +                           point);
>> +        return;
>> +    }
>>       if (fence)
>>           dma_fence_get(fence);
>>   @@ -174,28 +361,6 @@ void drm_syncobj_replace_fence(struct 
>> drm_syncobj *syncobj,
>>   }
>>   EXPORT_SYMBOL(drm_syncobj_replace_fence);
>>   -struct drm_syncobj_stub_fence {
>> -    struct dma_fence base;
>> -    spinlock_t lock;
>> -};
>> -
>> -static const char *drm_syncobj_stub_fence_get_name(struct dma_fence 
>> *fence)
>> -{
>> -        return "syncobjstub";
>> -}
>> -
>> -static bool drm_syncobj_stub_fence_enable_signaling(struct dma_fence 
>> *fence)
>> -{
>> -    return !dma_fence_is_signaled(fence);
>> -}
>> -
>> -static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>> -    .get_driver_name = drm_syncobj_stub_fence_get_name,
>> -    .get_timeline_name = drm_syncobj_stub_fence_get_name,
>> -    .enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>> -    .release = NULL,
>> -};
>> -
>>   static int drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>   {
>>       struct drm_syncobj_stub_fence *fence;
>> @@ -215,6 +380,121 @@ static int 
>> drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>       return 0;
>>   }
>>   +static struct drm_syncobj_wait_pt *
>> +drm_syncobj_timeline_lookup_wait_pt(struct drm_syncobj *syncobj, u64 
>> point)
>> +{
>> +    struct rb_node *node = 
>> syncobj->syncobj_timeline.wait_pt_tree.rb_node;
>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>> +
>> +
>> +    spin_lock(&syncobj->lock);
>> +    while(node) {
>> +        int result = point - wait_pt->value;
>> +
>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>> +        if (result < 0)
>> +            node = node->rb_left;
>> +        else if (result > 0)
>> +            node = node->rb_right;
>> +        else
>> +            break;
>> +    }
>> +    spin_unlock(&syncobj->lock);
>> +
>> +    return wait_pt;
>> +}
>> +
>> +static struct drm_syncobj_wait_pt *
>> +drm_syncobj_timeline_create_wait_pt(struct drm_syncobj *syncobj, u64 
>> point)
>> +{
>> +    struct drm_syncobj_wait_pt *wait_pt;
>> +    struct rb_node **new = 
>> &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
>> +
>> +    wait_pt = kzalloc(sizeof(*wait_pt), GFP_KERNEL);
>> +    if (!wait_pt)
>> +        return NULL;
>> +    spin_lock_init(&wait_pt->base.lock);
>> +    dma_fence_init(&wait_pt->base.base,
>> +               &drm_syncobj_stub_fence_ops,
>> +               &wait_pt->base.lock,
>> +               syncobj->syncobj_timeline.timeline_context, point);
>> +    wait_pt->value = point;
>> +
>> +    /* wait pt must be in an order, so that we can easily lookup and 
>> signal
>> +     * it */
>> +    spin_lock(&syncobj->lock);
>> +    if (point <= syncobj->syncobj_timeline.timeline)
>> +        dma_fence_signal(&wait_pt->base.base);
>> +    while(*new) {
>> +        struct drm_syncobj_wait_pt *this =
>> +            rb_entry(*new, struct drm_syncobj_wait_pt, node);
>> +        int result = wait_pt->value - this->value;
>> +
>> +        parent = *new;
>> +        if (result < 0)
>> +            new = &((*new)->rb_left);
>> +        else if (result > 0)
>> +            new = &((*new)->rb_right);
>> +        else
>> +            goto exist;
>> +    }
>> +
>> +    rb_link_node(&wait_pt->node, parent, new);
>> +    rb_insert_color(&wait_pt->node, 
>> &syncobj->syncobj_timeline.wait_pt_tree);
>> +    spin_unlock(&syncobj->lock);
>> +    return wait_pt;
>> +exist:
>> +    spin_unlock(&syncobj->lock);
>> +    dma_fence_put(&wait_pt->base.base);
>> +    wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
>> +    return wait_pt;
>> +}
>> +
>> +static struct dma_fence *
>> +drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 
>> point, u64 flag)
>> +{
>> +    struct drm_syncobj_wait_pt *wait_pt;
>> +
>> +    /* already signaled, simply return a signaled stub fence */
>> +    if (point <= syncobj->syncobj_timeline.timeline) {
>> +        struct drm_syncobj_stub_fence *fence;
>> +
>> +        fence = kzalloc(sizeof(*fence), GFP_KERNEL);
>> +        if (fence == NULL)
>> +            return NULL;
>> +
>> +        spin_lock_init(&fence->lock);
>> +        dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
>> +                   &fence->lock, 0, 0);
>> +        dma_fence_signal(&fence->base);
>> +        return &fence->base;
>> +    }
>> +
>> +    /* check if the wait pt exists */
>> +    wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
>> +    if (!wait_pt) {
>> +        /* This is a new wait pt, so create it */
>> +        wait_pt = drm_syncobj_timeline_create_wait_pt(syncobj, point);
>> +        if (!wait_pt)
>> +            return NULL;
>> +    }
>> +    if (wait_pt) {
>> +        struct dma_fence *fence;
>> +        int ret =
>> + wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
>> +                wait_pt->value <= 
>> syncobj->syncobj_timeline.signal_point,
>> +                msecs_to_jiffies(10000)); /* wait 10s */
>> +
>> +        if (ret <= 0)
>> +            return NULL;
>> +        rcu_read_lock();
>> +        fence = dma_fence_get_rcu(&wait_pt->base.base);
>> +        rcu_read_unlock();
>> +        return fence;
>> +    }
>> +    return NULL;
>> +}
>> +
>>   /**
>>    * drm_syncobj_find_fence - lookup and reference the fence in a 
>> sync object
>>    * @file_private: drm file private pointer
>> @@ -240,7 +520,17 @@ int drm_syncobj_find_fence(struct drm_file 
>> *file_private,
>>       if (!syncobj)
>>           return -ENOENT;
>>   -    *fence = drm_syncobj_fence_get(syncobj);
>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
>> +        /* NORMAL syncobj doesn't care point value */
>> +        WARN_ON(point != 0);
>> +        *fence = drm_syncobj_fence_get(syncobj);
>> +    } else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>> +        *fence = drm_syncobj_timeline_point_get(syncobj, point,
>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT);
>> +    } else {
>> +        DRM_ERROR("Don't support this type syncobj\n");
>> +        *fence = NULL;
>> +    }
>>       if (!*fence) {
>>           ret = -EINVAL;
>>       }
>> @@ -249,6 +539,34 @@ int drm_syncobj_find_fence(struct drm_file 
>> *file_private,
>>   }
>>   EXPORT_SYMBOL(drm_syncobj_find_fence);
>>   +static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
>> +                      struct drm_syncobj_timeline *syncobj_timeline)
>> +{
>> +    struct rb_node *node = NULL;
>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>> +    struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
>> +
>> +    spin_lock(&syncobj->lock);
>> +    for(node = rb_first(&syncobj_timeline->wait_pt_tree);
>> +        node != NULL; ) {
>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>> +        node = rb_next(node);
>> +        rb_erase(&wait_pt->node,
>> +             &syncobj_timeline->wait_pt_tree);
>> +        RB_CLEAR_NODE(&wait_pt->node);
>> +        /* kfree(wait_pt) is excuted by fence put */
>> +        dma_fence_put(&wait_pt->base.base);
>> +    }
>> +    list_for_each_entry_safe(signal_pt, tmp,
>> +                 &syncobj_timeline->signal_pt_list, list) {
>> +        list_del(&signal_pt->list);
>> +        dma_fence_put(signal_pt->signal_fence);
>> +        dma_fence_put(signal_pt->pre_pt_base);
>> +        dma_fence_put(&signal_pt->base.base);
>> +    }
>> +    spin_unlock(&syncobj->lock);
>> +}
>> +
>>   /**
>>    * drm_syncobj_free - free a sync object.
>>    * @kref: kref to free.
>> @@ -261,10 +579,23 @@ void drm_syncobj_free(struct kref *kref)
>>                              struct drm_syncobj,
>>                              refcount);
>>       drm_syncobj_replace_fence(syncobj, NULL, 0);
>> +    drm_syncobj_timeline_fini(syncobj, &syncobj->syncobj_timeline);
>>       kfree(syncobj);
>>   }
>>   EXPORT_SYMBOL(drm_syncobj_free);
>>   +static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
>> +                      *syncobj_timeline)
>> +{
>> +    syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
>> +    syncobj_timeline->timeline = 0;
>> +    syncobj_timeline->signal_point = 0;
>> +    init_waitqueue_head(&syncobj_timeline->wq);
>> +
>> +    syncobj_timeline->wait_pt_tree = RB_ROOT;
>> +    INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
>> +}
>> +
>>   /**
>>    * drm_syncobj_create - create a new syncobj
>>    * @out_syncobj: returned syncobj
>> @@ -290,6 +621,12 @@ int drm_syncobj_create(struct drm_syncobj 
>> **out_syncobj, uint32_t flags,
>>       kref_init(&syncobj->refcount);
>>       INIT_LIST_HEAD(&syncobj->cb_list);
>>       spin_lock_init(&syncobj->lock);
>> +    if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) {
>> +        syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
>> + drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
>> +    } else {
>> +        syncobj->type = DRM_SYNCOBJ_TYPE_NORMAL;
>> +    }
>>         if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
>>           ret = drm_syncobj_assign_null_handle(syncobj);
>> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
>> index 335ec501001a..342b3ced3e56 100644
>> --- a/include/drm/drm_syncobj.h
>> +++ b/include/drm/drm_syncobj.h
>> @@ -30,6 +30,25 @@
>>     struct drm_syncobj_cb;
>>   +enum drm_syncobj_type {
>> +    DRM_SYNCOBJ_TYPE_NORMAL,
>> +    DRM_SYNCOBJ_TYPE_TIMELINE
>> +};
>> +
>> +struct drm_syncobj_timeline {
>> +    wait_queue_head_t    wq;
>> +    u64 timeline_context;
>> +    /**
>> +     * @timeline: syncobj timeline
>> +     */
>> +    u64 timeline;
>> +    u64 signal_point;
>> +
>> +
>> +    struct rb_root wait_pt_tree;
>> +    struct list_head signal_pt_list;
>> +};
>> +
>>   /**
>>    * struct drm_syncobj - sync object.
>>    *
>> @@ -40,6 +59,15 @@ struct drm_syncobj {
>>        * @refcount: Reference count of this object.
>>        */
>>       struct kref refcount;
>> +    /**
>> +     * @type: indicate syncobj type
>> +     */
>> +    enum drm_syncobj_type type;
>> +    /**
>> +     * @syncobj_timeline: timeline
>> +     */
>> +    struct drm_syncobj_timeline syncobj_timeline;
>> +
>>       /**
>>        * @fence:
>>        * NULL or a pointer to the fence bound to this object.
>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>> index 300f336633f2..cebdb2541eb7 100644
>> --- a/include/uapi/drm/drm.h
>> +++ b/include/uapi/drm/drm.h
>> @@ -717,6 +717,7 @@ struct drm_prime_handle {
>>   struct drm_syncobj_create {
>>       __u32 handle;
>>   #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
>> +#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
>>       __u32 flags;
>>   };
>
Am 23.08.2018 um 11:58 schrieb zhoucm1:
>
>
> On 2018年08月23日 17:15, Christian König wrote:
>> Am 23.08.2018 um 10:25 schrieb Chunming Zhou:
>>> VK_KHR_timeline_semaphore:
>>> This extension introduces a new type of semaphore that has an 
>>> integer payload
>>> identifying a point in a timeline. Such timeline semaphores support the
>>> following operations:
>>>     * Host query - A host operation that allows querying the payload 
>>> of the
>>>       timeline semaphore.
>>>     * Host wait - A host operation that allows a blocking wait for a
>>>       timeline semaphore to reach a specified value.
>>
>> I think I have a idea what "Host" means in this context, but it would 
>> probably be better to describe it.
>
> How about "CPU"?


Yeah, that's probably better.

>
>>>     * Device wait - A device operation that allows waiting for a
>>>       timeline semaphore to reach a specified value.
>>>     * Device signal - A device operation that allows advancing the
>>>       timeline semaphore to a specified value.
>>>
>>> Since it's a timeline, that means the front time point(PT) always is 
>>> signaled before the late PT.
>>> a. signal PT design:
>>> Signal PT fence N depends on PT[N-1] fence and signal opertion 
>>> fence, when PT[N] fence is signaled,
>>> the timeline will increase to value of PT[N].
>>> b. wait PT design:
>>> Wait PT fence is signaled by reaching timeline point value, when 
>>> timeline is increasing, will compare
>>> wait PTs value with new timeline value, if PT value is lower than 
>>> timeline value, then wait PT will be
>>> signaled, otherwise keep in list. semaphore wait operation can wait 
>>> on any point of timeline,
>>> so need a RB tree to order them. And wait PT could ahead of signal 
>>> PT, we need a sumission fence to
>>> perform that.
>>>
>>> v2:
>>> 1. remove unused DRM_SYNCOBJ_CREATE_TYPE_NORMAL. (Christian)
>>> 2. move unexposed denitions to .c file. (Daniel Vetter)
>>> 3. split up the change to drm_syncobj_find_fence() in a separate 
>>> patch. (Christian)
>>> 4. split up the change to drm_syncobj_replace_fence() in a separate 
>>> patch.
>>> 5. drop the submission_fence implementation and instead use 
>>> wait_event() for that. (Christian)
>>> 6. WARN_ON(point != 0) for NORMAL type syncobj case. (Daniel Vetter)
>>
>> I really liked Daniels idea to handle the classic syncobj like a 
>> timeline synobj with just 1 entry. That can probably simplify the 
>> implementation quite a bit.
> Yeah, after timeline, seems we can remove old syncobj->fence, right? 
> will try to unify them in additional patch.

I think we could do something like the following:

1. When drm_syncobj_find_fence is called with point zero then we return 
the last added one.
2. When drm_syncobj_find_fence is called with point zero we add the new 
fence as with N+1 to the list.

This way syncobj should keep it's functionality as is with the timeline 
support added on top.

Regards,
Christian.

>
> Thanks,
> David Zhou
>>
>> Additional to that an amdgpu patch which shows how the interface is 
>> to be used is probably something Daniel will want to see as well.
>>
>> Christian.
>>
>>>
>>> TODO:
>>> 1. CPU query and wait on timeline semaphore.
>>> 2. test application (Daniel Vetter)
>>>
>>> Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
>>> Cc: Christian Konig <christian.koenig@amd.com>
>>> Cc: Dave Airlie <airlied@redhat.com>
>>> Cc: Daniel Rakos <Daniel.Rakos@amd.com>
>>> Cc: Daniel Vetter <daniel@ffwll.ch>
>>> ---
>>>   drivers/gpu/drm/drm_syncobj.c | 383 
>>> +++++++++++++++++++++++++++++++++++++++---
>>>   include/drm/drm_syncobj.h     |  28 +++
>>>   include/uapi/drm/drm.h        |   1 +
>>>   3 files changed, 389 insertions(+), 23 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/drm_syncobj.c 
>>> b/drivers/gpu/drm/drm_syncobj.c
>>> index 6227df2cc0a4..f738d78edf65 100644
>>> --- a/drivers/gpu/drm/drm_syncobj.c
>>> +++ b/drivers/gpu/drm/drm_syncobj.c
>>> @@ -56,6 +56,44 @@
>>>   #include "drm_internal.h"
>>>   #include <drm/drm_syncobj.h>
>>>   +struct drm_syncobj_stub_fence {
>>> +    struct dma_fence base;
>>> +    spinlock_t lock;
>>> +};
>>> +
>>> +static const char *drm_syncobj_stub_fence_get_name(struct dma_fence 
>>> *fence)
>>> +{
>>> +        return "syncobjstub";
>>> +}
>>> +
>>> +static bool drm_syncobj_stub_fence_enable_signaling(struct 
>>> dma_fence *fence)
>>> +{
>>> +    return !dma_fence_is_signaled(fence);
>>> +}
>>> +
>>> +static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>>> +    .get_driver_name = drm_syncobj_stub_fence_get_name,
>>> +    .get_timeline_name = drm_syncobj_stub_fence_get_name,
>>> +    .enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>>> +    .release = NULL,
>>> +};
>>> +
>>> +struct drm_syncobj_wait_pt {
>>> +    struct drm_syncobj_stub_fence base;
>>> +    u64    value;
>>> +    struct rb_node   node;
>>> +};
>>> +struct drm_syncobj_signal_pt {
>>> +    struct drm_syncobj_stub_fence base;
>>> +    struct dma_fence *signal_fence;
>>> +    struct dma_fence *pre_pt_base;
>>> +    struct dma_fence_cb signal_cb;
>>> +    struct dma_fence_cb pre_pt_cb;
>>> +    struct drm_syncobj *syncobj;
>>> +    u64    value;
>>> +    struct list_head list;
>>> +};
>>> +
>>>   /**
>>>    * drm_syncobj_find - lookup and reference a sync object.
>>>    * @file_private: drm file private pointer
>>> @@ -137,6 +175,150 @@ void drm_syncobj_remove_callback(struct 
>>> drm_syncobj *syncobj,
>>>       spin_unlock(&syncobj->lock);
>>>   }
>>>   +static void drm_syncobj_timeline_signal_wait_pts(struct 
>>> drm_syncobj *syncobj)
>>> +{
>>> +    struct rb_node *node = NULL;
>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>> +
>>> +    spin_lock(&syncobj->lock);
>>> +    for(node = rb_first(&syncobj->syncobj_timeline.wait_pt_tree);
>>> +        node != NULL; ) {
>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>> +        node = rb_next(node);
>>> +        if (wait_pt->value <= syncobj->syncobj_timeline.timeline) {
>>> +            dma_fence_signal(&wait_pt->base.base);
>>> +            rb_erase(&wait_pt->node,
>>> + &syncobj->syncobj_timeline.wait_pt_tree);
>>> +            RB_CLEAR_NODE(&wait_pt->node);
>>> +            /* kfree(wait_pt) is excuted by fence put */
>>> +            dma_fence_put(&wait_pt->base.base);
>>> +        } else {
>>> +            /* the loop is from left to right, the later entry 
>>> value is
>>> +             * bigger, so don't need to check any more */
>>> +            break;
>>> +        }
>>> +    }
>>> +    spin_unlock(&syncobj->lock);
>>> +}
>>> +
>>> +
>>> +static void pt_fence_cb(struct drm_syncobj_signal_pt *signal_pt)
>>> +{
>>> +    struct dma_fence *fence = NULL;
>>> +    struct drm_syncobj *syncobj;
>>> +
>>> +    fence = signal_pt->signal_fence;
>>> +    signal_pt->signal_fence = NULL;
>>> +    dma_fence_put(fence);
>>> +    fence = signal_pt->pre_pt_base;
>>> +    signal_pt->pre_pt_base = NULL;
>>> +    dma_fence_put(fence);
>>> +
>>> +    syncobj = signal_pt->syncobj;
>>> +    spin_lock(&syncobj->lock);
>>> +    list_del(&signal_pt->list);
>>> +    syncobj->syncobj_timeline.timeline = signal_pt->value;
>>> +    spin_unlock(&syncobj->lock);
>>> +    /* kfree(signal_pt) will be  executed by below fence put */
>>> +    dma_fence_put(&signal_pt->base.base);
>>> +    drm_syncobj_timeline_signal_wait_pts(syncobj);
>>> +}
>>> +static void pt_signal_fence_func(struct dma_fence *fence,
>>> +                 struct dma_fence_cb *cb)
>>> +{
>>> +    struct drm_syncobj_signal_pt *signal_pt =
>>> +        container_of(cb, struct drm_syncobj_signal_pt, signal_cb);
>>> +
>>> +    if (signal_pt->pre_pt_base &&
>>> +        !dma_fence_is_signaled(signal_pt->pre_pt_base))
>>> +        return;
>>> +
>>> +    pt_fence_cb(signal_pt);
>>> +}
>>> +static void pt_pre_fence_func(struct dma_fence *fence,
>>> +                 struct dma_fence_cb *cb)
>>> +{
>>> +    struct drm_syncobj_signal_pt *signal_pt =
>>> +        container_of(cb, struct drm_syncobj_signal_pt, pre_pt_cb);
>>> +
>>> +    if (signal_pt->signal_fence &&
>>> +        !dma_fence_is_signaled(signal_pt->pre_pt_base))
>>> +        return;
>>> +
>>> +    pt_fence_cb(signal_pt);
>>> +}
>>> +
>>> +static int drm_syncobj_timeline_replace_fence(struct drm_syncobj 
>>> *syncobj,
>>> +                          struct dma_fence *fence,
>>> +                          u64 point)
>>> +{
>>> +    struct drm_syncobj_signal_pt *signal_pt =
>>> +        kzalloc(sizeof(struct drm_syncobj_signal_pt), GFP_KERNEL);
>>> +    struct drm_syncobj_signal_pt *tail_pt;
>>> +    struct dma_fence *tail_pt_fence = NULL;
>>> +    int ret = 0;
>>> +
>>> +    if (!signal_pt)
>>> +        return -ENOMEM;
>>> +    if (syncobj->syncobj_timeline.signal_point >= point) {
>>> +        DRM_WARN("A later signal is ready!");
>>> +        goto out;
>>> +    }
>>> +    if (fence)
>>> +        dma_fence_get(fence);
>>> +    spin_lock(&syncobj->lock);
>>> +    spin_lock_init(&signal_pt->base.lock);
>>> +    dma_fence_init(&signal_pt->base.base,
>>> +               &drm_syncobj_stub_fence_ops,
>>> +               &signal_pt->base.lock,
>>> +               syncobj->syncobj_timeline.timeline_context, point);
>>> +    signal_pt->signal_fence =
>>> +        rcu_dereference_protected(fence,
>>> +                      lockdep_is_held(&fence->lock));
>>> +    if (!list_empty(&syncobj->syncobj_timeline.signal_pt_list)) {
>>> +        tail_pt = 
>>> list_last_entry(&syncobj->syncobj_timeline.signal_pt_list,
>>> +                      struct drm_syncobj_signal_pt, list);
>>> +        tail_pt_fence = &tail_pt->base.base;
>>> +        if (dma_fence_is_signaled(tail_pt_fence))
>>> +            tail_pt_fence = NULL;
>>> +    }
>>> +    if (tail_pt_fence)
>>> +        signal_pt->pre_pt_base =
>>> + dma_fence_get(rcu_dereference_protected(tail_pt_fence,
>>> + lockdep_is_held(&tail_pt_fence->lock)));
>>> +
>>> +    signal_pt->value = point;
>>> +    syncobj->syncobj_timeline.signal_point = point;
>>> +    signal_pt->syncobj = syncobj;
>>> +    INIT_LIST_HEAD(&signal_pt->list);
>>> +    list_add_tail(&signal_pt->list, 
>>> &syncobj->syncobj_timeline.signal_pt_list);
>>> +    spin_unlock(&syncobj->lock);
>>> +    wake_up_all(&syncobj->syncobj_timeline.wq);
>>> +    /**
>>> +     * Every pt is depending on signal fence and previous pt fence, 
>>> add
>>> +     * callbacks to them
>>> +     */
>>> +    if (!dma_fence_is_signaled(signal_pt->signal_fence))
>>> +        dma_fence_add_callback(signal_pt->signal_fence,
>>> +                       &signal_pt->signal_cb,
>>> +                       pt_signal_fence_func);
>>> +    else
>>> +        pt_signal_fence_func(signal_pt->signal_fence,
>>> +                     &signal_pt->signal_cb);
>>> +    if (signal_pt->pre_pt_base && 
>>> !dma_fence_is_signaled(signal_pt->pre_pt_base))
>>> +        dma_fence_add_callback(signal_pt->pre_pt_base,
>>> +                       &signal_pt->pre_pt_cb,
>>> +                       pt_pre_fence_func);
>>> +    else
>>> +        pt_pre_fence_func(signal_pt->pre_pt_base, 
>>> &signal_pt->pre_pt_cb);
>>> +
>>> +
>>> +    return 0;
>>> +out:
>>> +    kfree(signal_pt);
>>> +    return ret;
>>> +}
>>> +
>>>   /**
>>>    * drm_syncobj_replace_fence - replace fence in a sync object.
>>>    * @syncobj: Sync object to replace fence in
>>> @@ -152,6 +334,11 @@ void drm_syncobj_replace_fence(struct 
>>> drm_syncobj *syncobj,
>>>       struct dma_fence *old_fence;
>>>       struct drm_syncobj_cb *cur, *tmp;
>>>   +    if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>> +        drm_syncobj_timeline_replace_fence(syncobj, fence,
>>> +                           point);
>>> +        return;
>>> +    }
>>>       if (fence)
>>>           dma_fence_get(fence);
>>>   @@ -174,28 +361,6 @@ void drm_syncobj_replace_fence(struct 
>>> drm_syncobj *syncobj,
>>>   }
>>>   EXPORT_SYMBOL(drm_syncobj_replace_fence);
>>>   -struct drm_syncobj_stub_fence {
>>> -    struct dma_fence base;
>>> -    spinlock_t lock;
>>> -};
>>> -
>>> -static const char *drm_syncobj_stub_fence_get_name(struct dma_fence 
>>> *fence)
>>> -{
>>> -        return "syncobjstub";
>>> -}
>>> -
>>> -static bool drm_syncobj_stub_fence_enable_signaling(struct 
>>> dma_fence *fence)
>>> -{
>>> -    return !dma_fence_is_signaled(fence);
>>> -}
>>> -
>>> -static const struct dma_fence_ops drm_syncobj_stub_fence_ops = {
>>> -    .get_driver_name = drm_syncobj_stub_fence_get_name,
>>> -    .get_timeline_name = drm_syncobj_stub_fence_get_name,
>>> -    .enable_signaling = drm_syncobj_stub_fence_enable_signaling,
>>> -    .release = NULL,
>>> -};
>>> -
>>>   static int drm_syncobj_assign_null_handle(struct drm_syncobj 
>>> *syncobj)
>>>   {
>>>       struct drm_syncobj_stub_fence *fence;
>>> @@ -215,6 +380,121 @@ static int 
>>> drm_syncobj_assign_null_handle(struct drm_syncobj *syncobj)
>>>       return 0;
>>>   }
>>>   +static struct drm_syncobj_wait_pt *
>>> +drm_syncobj_timeline_lookup_wait_pt(struct drm_syncobj *syncobj, 
>>> u64 point)
>>> +{
>>> +    struct rb_node *node = 
>>> syncobj->syncobj_timeline.wait_pt_tree.rb_node;
>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>> +
>>> +
>>> +    spin_lock(&syncobj->lock);
>>> +    while(node) {
>>> +        int result = point - wait_pt->value;
>>> +
>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>> +        if (result < 0)
>>> +            node = node->rb_left;
>>> +        else if (result > 0)
>>> +            node = node->rb_right;
>>> +        else
>>> +            break;
>>> +    }
>>> +    spin_unlock(&syncobj->lock);
>>> +
>>> +    return wait_pt;
>>> +}
>>> +
>>> +static struct drm_syncobj_wait_pt *
>>> +drm_syncobj_timeline_create_wait_pt(struct drm_syncobj *syncobj, 
>>> u64 point)
>>> +{
>>> +    struct drm_syncobj_wait_pt *wait_pt;
>>> +    struct rb_node **new = 
>>> &(syncobj->syncobj_timeline.wait_pt_tree.rb_node), *parent = NULL;
>>> +
>>> +    wait_pt = kzalloc(sizeof(*wait_pt), GFP_KERNEL);
>>> +    if (!wait_pt)
>>> +        return NULL;
>>> +    spin_lock_init(&wait_pt->base.lock);
>>> +    dma_fence_init(&wait_pt->base.base,
>>> +               &drm_syncobj_stub_fence_ops,
>>> +               &wait_pt->base.lock,
>>> +               syncobj->syncobj_timeline.timeline_context, point);
>>> +    wait_pt->value = point;
>>> +
>>> +    /* wait pt must be in an order, so that we can easily lookup 
>>> and signal
>>> +     * it */
>>> +    spin_lock(&syncobj->lock);
>>> +    if (point <= syncobj->syncobj_timeline.timeline)
>>> +        dma_fence_signal(&wait_pt->base.base);
>>> +    while(*new) {
>>> +        struct drm_syncobj_wait_pt *this =
>>> +            rb_entry(*new, struct drm_syncobj_wait_pt, node);
>>> +        int result = wait_pt->value - this->value;
>>> +
>>> +        parent = *new;
>>> +        if (result < 0)
>>> +            new = &((*new)->rb_left);
>>> +        else if (result > 0)
>>> +            new = &((*new)->rb_right);
>>> +        else
>>> +            goto exist;
>>> +    }
>>> +
>>> +    rb_link_node(&wait_pt->node, parent, new);
>>> +    rb_insert_color(&wait_pt->node, 
>>> &syncobj->syncobj_timeline.wait_pt_tree);
>>> +    spin_unlock(&syncobj->lock);
>>> +    return wait_pt;
>>> +exist:
>>> +    spin_unlock(&syncobj->lock);
>>> +    dma_fence_put(&wait_pt->base.base);
>>> +    wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
>>> +    return wait_pt;
>>> +}
>>> +
>>> +static struct dma_fence *
>>> +drm_syncobj_timeline_point_get(struct drm_syncobj *syncobj, u64 
>>> point, u64 flag)
>>> +{
>>> +    struct drm_syncobj_wait_pt *wait_pt;
>>> +
>>> +    /* already signaled, simply return a signaled stub fence */
>>> +    if (point <= syncobj->syncobj_timeline.timeline) {
>>> +        struct drm_syncobj_stub_fence *fence;
>>> +
>>> +        fence = kzalloc(sizeof(*fence), GFP_KERNEL);
>>> +        if (fence == NULL)
>>> +            return NULL;
>>> +
>>> +        spin_lock_init(&fence->lock);
>>> +        dma_fence_init(&fence->base, &drm_syncobj_stub_fence_ops,
>>> +                   &fence->lock, 0, 0);
>>> +        dma_fence_signal(&fence->base);
>>> +        return &fence->base;
>>> +    }
>>> +
>>> +    /* check if the wait pt exists */
>>> +    wait_pt = drm_syncobj_timeline_lookup_wait_pt(syncobj, point);
>>> +    if (!wait_pt) {
>>> +        /* This is a new wait pt, so create it */
>>> +        wait_pt = drm_syncobj_timeline_create_wait_pt(syncobj, point);
>>> +        if (!wait_pt)
>>> +            return NULL;
>>> +    }
>>> +    if (wait_pt) {
>>> +        struct dma_fence *fence;
>>> +        int ret =
>>> + wait_event_interruptible_timeout(syncobj->syncobj_timeline.wq,
>>> +                wait_pt->value <= 
>>> syncobj->syncobj_timeline.signal_point,
>>> +                msecs_to_jiffies(10000)); /* wait 10s */
>>> +
>>> +        if (ret <= 0)
>>> +            return NULL;
>>> +        rcu_read_lock();
>>> +        fence = dma_fence_get_rcu(&wait_pt->base.base);
>>> +        rcu_read_unlock();
>>> +        return fence;
>>> +    }
>>> +    return NULL;
>>> +}
>>> +
>>>   /**
>>>    * drm_syncobj_find_fence - lookup and reference the fence in a 
>>> sync object
>>>    * @file_private: drm file private pointer
>>> @@ -240,7 +520,17 @@ int drm_syncobj_find_fence(struct drm_file 
>>> *file_private,
>>>       if (!syncobj)
>>>           return -ENOENT;
>>>   -    *fence = drm_syncobj_fence_get(syncobj);
>>> +    if (syncobj->type == DRM_SYNCOBJ_TYPE_NORMAL) {
>>> +        /* NORMAL syncobj doesn't care point value */
>>> +        WARN_ON(point != 0);
>>> +        *fence = drm_syncobj_fence_get(syncobj);
>>> +    } else if (syncobj->type == DRM_SYNCOBJ_TYPE_TIMELINE) {
>>> +        *fence = drm_syncobj_timeline_point_get(syncobj, point,
>>> + DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT);
>>> +    } else {
>>> +        DRM_ERROR("Don't support this type syncobj\n");
>>> +        *fence = NULL;
>>> +    }
>>>       if (!*fence) {
>>>           ret = -EINVAL;
>>>       }
>>> @@ -249,6 +539,34 @@ int drm_syncobj_find_fence(struct drm_file 
>>> *file_private,
>>>   }
>>>   EXPORT_SYMBOL(drm_syncobj_find_fence);
>>>   +static void drm_syncobj_timeline_fini(struct drm_syncobj *syncobj,
>>> +                      struct drm_syncobj_timeline *syncobj_timeline)
>>> +{
>>> +    struct rb_node *node = NULL;
>>> +    struct drm_syncobj_wait_pt *wait_pt = NULL;
>>> +    struct drm_syncobj_signal_pt *signal_pt = NULL, *tmp;
>>> +
>>> +    spin_lock(&syncobj->lock);
>>> +    for(node = rb_first(&syncobj_timeline->wait_pt_tree);
>>> +        node != NULL; ) {
>>> +        wait_pt = rb_entry(node, struct drm_syncobj_wait_pt, node);
>>> +        node = rb_next(node);
>>> +        rb_erase(&wait_pt->node,
>>> +             &syncobj_timeline->wait_pt_tree);
>>> +        RB_CLEAR_NODE(&wait_pt->node);
>>> +        /* kfree(wait_pt) is excuted by fence put */
>>> +        dma_fence_put(&wait_pt->base.base);
>>> +    }
>>> +    list_for_each_entry_safe(signal_pt, tmp,
>>> +                 &syncobj_timeline->signal_pt_list, list) {
>>> +        list_del(&signal_pt->list);
>>> +        dma_fence_put(signal_pt->signal_fence);
>>> +        dma_fence_put(signal_pt->pre_pt_base);
>>> +        dma_fence_put(&signal_pt->base.base);
>>> +    }
>>> +    spin_unlock(&syncobj->lock);
>>> +}
>>> +
>>>   /**
>>>    * drm_syncobj_free - free a sync object.
>>>    * @kref: kref to free.
>>> @@ -261,10 +579,23 @@ void drm_syncobj_free(struct kref *kref)
>>>                              struct drm_syncobj,
>>>                              refcount);
>>>       drm_syncobj_replace_fence(syncobj, NULL, 0);
>>> +    drm_syncobj_timeline_fini(syncobj, &syncobj->syncobj_timeline);
>>>       kfree(syncobj);
>>>   }
>>>   EXPORT_SYMBOL(drm_syncobj_free);
>>>   +static void drm_syncobj_timeline_init(struct drm_syncobj_timeline
>>> +                      *syncobj_timeline)
>>> +{
>>> +    syncobj_timeline->timeline_context = dma_fence_context_alloc(1);
>>> +    syncobj_timeline->timeline = 0;
>>> +    syncobj_timeline->signal_point = 0;
>>> +    init_waitqueue_head(&syncobj_timeline->wq);
>>> +
>>> +    syncobj_timeline->wait_pt_tree = RB_ROOT;
>>> +    INIT_LIST_HEAD(&syncobj_timeline->signal_pt_list);
>>> +}
>>> +
>>>   /**
>>>    * drm_syncobj_create - create a new syncobj
>>>    * @out_syncobj: returned syncobj
>>> @@ -290,6 +621,12 @@ int drm_syncobj_create(struct drm_syncobj 
>>> **out_syncobj, uint32_t flags,
>>>       kref_init(&syncobj->refcount);
>>>       INIT_LIST_HEAD(&syncobj->cb_list);
>>>       spin_lock_init(&syncobj->lock);
>>> +    if (flags & DRM_SYNCOBJ_CREATE_TYPE_TIMELINE) {
>>> +        syncobj->type = DRM_SYNCOBJ_TYPE_TIMELINE;
>>> + drm_syncobj_timeline_init(&syncobj->syncobj_timeline);
>>> +    } else {
>>> +        syncobj->type = DRM_SYNCOBJ_TYPE_NORMAL;
>>> +    }
>>>         if (flags & DRM_SYNCOBJ_CREATE_SIGNALED) {
>>>           ret = drm_syncobj_assign_null_handle(syncobj);
>>> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
>>> index 335ec501001a..342b3ced3e56 100644
>>> --- a/include/drm/drm_syncobj.h
>>> +++ b/include/drm/drm_syncobj.h
>>> @@ -30,6 +30,25 @@
>>>     struct drm_syncobj_cb;
>>>   +enum drm_syncobj_type {
>>> +    DRM_SYNCOBJ_TYPE_NORMAL,
>>> +    DRM_SYNCOBJ_TYPE_TIMELINE
>>> +};
>>> +
>>> +struct drm_syncobj_timeline {
>>> +    wait_queue_head_t    wq;
>>> +    u64 timeline_context;
>>> +    /**
>>> +     * @timeline: syncobj timeline
>>> +     */
>>> +    u64 timeline;
>>> +    u64 signal_point;
>>> +
>>> +
>>> +    struct rb_root wait_pt_tree;
>>> +    struct list_head signal_pt_list;
>>> +};
>>> +
>>>   /**
>>>    * struct drm_syncobj - sync object.
>>>    *
>>> @@ -40,6 +59,15 @@ struct drm_syncobj {
>>>        * @refcount: Reference count of this object.
>>>        */
>>>       struct kref refcount;
>>> +    /**
>>> +     * @type: indicate syncobj type
>>> +     */
>>> +    enum drm_syncobj_type type;
>>> +    /**
>>> +     * @syncobj_timeline: timeline
>>> +     */
>>> +    struct drm_syncobj_timeline syncobj_timeline;
>>> +
>>>       /**
>>>        * @fence:
>>>        * NULL or a pointer to the fence bound to this object.
>>> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
>>> index 300f336633f2..cebdb2541eb7 100644
>>> --- a/include/uapi/drm/drm.h
>>> +++ b/include/uapi/drm/drm.h
>>> @@ -717,6 +717,7 @@ struct drm_prime_handle {
>>>   struct drm_syncobj_create {
>>>       __u32 handle;
>>>   #define DRM_SYNCOBJ_CREATE_SIGNALED (1 << 0)
>>> +#define DRM_SYNCOBJ_CREATE_TYPE_TIMELINE (1 << 1)
>>>       __u32 flags;
>>>   };
>>
>
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