[v5] drm/i915: Pin the ifbdev for the info->system_base GGTT mmapping

Submitted by Chris Wilson on Dec. 4, 2015, 4:05 p.m.

Details

Message ID 1449245126-26158-1-git-send-email-chris@chris-wilson.co.uk
State Accepted
Commit 0c82312f3f15538f4e6ceda2a82caee8fbac4501
Headers show
Series "Series without cover letter" ( rev: 4 ) in Intel GFX

Not browsing as part of any series.

Commit Message

Chris Wilson Dec. 4, 2015, 4:05 p.m.
A long time ago (before 3.14) we relied on a permanent pinning of the
ifbdev to lock the fb in place inside the GGTT. However, the
introduction of stealing the BIOS framebuffer and reusing its address in
the GGTT for the fbdev has muddied waters and we use an inherited fb.
However, the inherited fb is only pinned whilst it is active and we no
longer have an explicit pin for the info->system_base mmapping used by
the fbdev. The result is that after some aperture pressure the fbdev may
be evicted, but we continue to write the fbcon into the same GGTT
address - overwriting anything else that may be put into that offset.
The effect is most pronounced across suspend/resume as
intel_fbdev_set_suspend() does a full clear over the whole scanout.

v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
the BIOS, we do not own the pinned vma (except for the reference we add
in this patch for our access via info->screen_base).

v3: Finish balancing the vma pinning for the normal !preallocated case.

v4: Try to simplify the pinning even further.
v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Goel, Akash" <akash.goel@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org
---
 drivers/gpu/drm/i915/intel_fbdev.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 7ccde58f8c98..bea75cafc623 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -163,13 +163,6 @@  static int intelfb_alloc(struct drm_fb_helper *helper,
 		goto out;
 	}
 
-	/* Flush everything out, we'll be doing GTT only from now on */
-	ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL);
-	if (ret) {
-		DRM_ERROR("failed to pin obj: %d\n", ret);
-		goto out;
-	}
-
 	mutex_unlock(&dev->struct_mutex);
 
 	ifbdev->fb = to_intel_framebuffer(fb);
@@ -225,6 +218,14 @@  static int intelfb_create(struct drm_fb_helper *helper,
 
 	mutex_lock(&dev->struct_mutex);
 
+	/* Pin the GGTT vma for our access via info->screen_base.
+	 * This also validates that any existing fb inherited from the
+	 * BIOS is suitable for own access.
+	 */
+	ret = intel_pin_and_fence_fb_obj(NULL, &ifbdev->fb->base, NULL);
+	if (ret)
+		goto out_unlock;
+
 	info = drm_fb_helper_alloc_fbi(helper);
 	if (IS_ERR(info)) {
 		DRM_ERROR("Failed to allocate fb_info\n");
@@ -287,6 +288,7 @@  out_destroy_fbi:
 	drm_fb_helper_release_fbi(helper);
 out_unpin:
 	i915_gem_object_ggtt_unpin(obj);
+out_unlock:
 	mutex_unlock(&dev->struct_mutex);
 	return ret;
 }
@@ -524,6 +526,10 @@  static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
 static void intel_fbdev_destroy(struct drm_device *dev,
 				struct intel_fbdev *ifbdev)
 {
+	/* We rely on the object-free to release the VMA pinning for
+	 * the info->screen_base mmaping. Leaking the VMA is simpler than
+	 * trying to rectify all the possible error paths leading here.
+	 */
 
 	drm_fb_helper_unregister_fbi(&ifbdev->helper);
 	drm_fb_helper_release_fbi(&ifbdev->helper);

Comments

Hi Chris,

On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> A long time ago (before 3.14) we relied on a permanent pinning of the
> ifbdev to lock the fb in place inside the GGTT. However, the
> introduction of stealing the BIOS framebuffer and reusing its address in
> the GGTT for the fbdev has muddied waters and we use an inherited fb.
> However, the inherited fb is only pinned whilst it is active and we no
> longer have an explicit pin for the info->system_base mmapping used by
> the fbdev. The result is that after some aperture pressure the fbdev may
> be evicted, but we continue to write the fbcon into the same GGTT
> address - overwriting anything else that may be put into that offset.
> The effect is most pronounced across suspend/resume as
> intel_fbdev_set_suspend() does a full clear over the whole scanout.
> 
> v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> the BIOS, we do not own the pinned vma (except for the reference we add
> in this patch for our access via info->screen_base).
> 
> v3: Finish balancing the vma pinning for the normal !preallocated case.
> 
> v4: Try to simplify the pinning even further.
> v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.

It's beautiful how little code is needed to fix this. The only remaining
thing I noticed now while looking over the error paths is that these
lines in intelfb_alloc() become obsolete with your patch:

 out:
 	mutex_unlock(&dev->struct_mutex);
-	if (!IS_ERR_OR_NULL(fb))
-		drm_framebuffer_unreference(fb);
 	return ret;
 }

Because at each of the remaining "goto out" in the function,
fb can be only either an ERR_PTR or NULL.

Also, further up in the function, the declaration of fb can then be
changed thus:

-	struct drm_framebuffer *fb = NULL;
+	struct drm_framebuffer *fb;

Kind regards,

Lukas

> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: "Goel, Akash" <akash.goel@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> Cc: Lukas Wunner <lukas@wunner.de>
> Cc: stable@vger.kernel.org
> ---
>  drivers/gpu/drm/i915/intel_fbdev.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index 7ccde58f8c98..bea75cafc623 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -163,13 +163,6 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
>  		goto out;
>  	}
>  
> -	/* Flush everything out, we'll be doing GTT only from now on */
> -	ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL);
> -	if (ret) {
> -		DRM_ERROR("failed to pin obj: %d\n", ret);
> -		goto out;
> -	}
> -
>  	mutex_unlock(&dev->struct_mutex);
>  
>  	ifbdev->fb = to_intel_framebuffer(fb);
> @@ -225,6 +218,14 @@ static int intelfb_create(struct drm_fb_helper *helper,
>  
>  	mutex_lock(&dev->struct_mutex);
>  
> +	/* Pin the GGTT vma for our access via info->screen_base.
> +	 * This also validates that any existing fb inherited from the
> +	 * BIOS is suitable for own access.
> +	 */
> +	ret = intel_pin_and_fence_fb_obj(NULL, &ifbdev->fb->base, NULL);
> +	if (ret)
> +		goto out_unlock;
> +
>  	info = drm_fb_helper_alloc_fbi(helper);
>  	if (IS_ERR(info)) {
>  		DRM_ERROR("Failed to allocate fb_info\n");
> @@ -287,6 +288,7 @@ out_destroy_fbi:
>  	drm_fb_helper_release_fbi(helper);
>  out_unpin:
>  	i915_gem_object_ggtt_unpin(obj);
> +out_unlock:
>  	mutex_unlock(&dev->struct_mutex);
>  	return ret;
>  }
> @@ -524,6 +526,10 @@ static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
>  static void intel_fbdev_destroy(struct drm_device *dev,
>  				struct intel_fbdev *ifbdev)
>  {
> +	/* We rely on the object-free to release the VMA pinning for
> +	 * the info->screen_base mmaping. Leaking the VMA is simpler than
> +	 * trying to rectify all the possible error paths leading here.
> +	 */
>  
>  	drm_fb_helper_unregister_fbi(&ifbdev->helper);
>  	drm_fb_helper_release_fbi(&ifbdev->helper);
> -- 
> 2.6.2
>
On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> A long time ago (before 3.14) we relied on a permanent pinning of the
> ifbdev to lock the fb in place inside the GGTT. However, the
> introduction of stealing the BIOS framebuffer and reusing its address in
> the GGTT for the fbdev has muddied waters and we use an inherited fb.
> However, the inherited fb is only pinned whilst it is active and we no
> longer have an explicit pin for the info->system_base mmapping used by
> the fbdev. The result is that after some aperture pressure the fbdev may
> be evicted, but we continue to write the fbcon into the same GGTT
> address - overwriting anything else that may be put into that offset.
> The effect is most pronounced across suspend/resume as
> intel_fbdev_set_suspend() does a full clear over the whole scanout.
> 
> v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> the BIOS, we do not own the pinned vma (except for the reference we add
> in this patch for our access via info->screen_base).
> 
> v3: Finish balancing the vma pinning for the normal !preallocated case.
> 
> v4: Try to simplify the pinning even further.
> v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: "Goel, Akash" <akash.goel@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> Cc: Lukas Wunner <lukas@wunner.de>
> Cc: stable@vger.kernel.org

This seems to have fixed my garbled text+fbcon dead after
suspend/hibernate issues. Well, only had the patch in for a day or so,
but so far so good.

Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Takashi, don't know if you already found this patch, but it's definitely
something you should try as well.

> ---
>  drivers/gpu/drm/i915/intel_fbdev.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> index 7ccde58f8c98..bea75cafc623 100644
> --- a/drivers/gpu/drm/i915/intel_fbdev.c
> +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> @@ -163,13 +163,6 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
>  		goto out;
>  	}
>  
> -	/* Flush everything out, we'll be doing GTT only from now on */
> -	ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL);
> -	if (ret) {
> -		DRM_ERROR("failed to pin obj: %d\n", ret);
> -		goto out;
> -	}
> -
>  	mutex_unlock(&dev->struct_mutex);
>  
>  	ifbdev->fb = to_intel_framebuffer(fb);
> @@ -225,6 +218,14 @@ static int intelfb_create(struct drm_fb_helper *helper,
>  
>  	mutex_lock(&dev->struct_mutex);
>  
> +	/* Pin the GGTT vma for our access via info->screen_base.
> +	 * This also validates that any existing fb inherited from the
> +	 * BIOS is suitable for own access.
> +	 */
> +	ret = intel_pin_and_fence_fb_obj(NULL, &ifbdev->fb->base, NULL);
> +	if (ret)
> +		goto out_unlock;
> +
>  	info = drm_fb_helper_alloc_fbi(helper);
>  	if (IS_ERR(info)) {
>  		DRM_ERROR("Failed to allocate fb_info\n");
> @@ -287,6 +288,7 @@ out_destroy_fbi:
>  	drm_fb_helper_release_fbi(helper);
>  out_unpin:
>  	i915_gem_object_ggtt_unpin(obj);
> +out_unlock:
>  	mutex_unlock(&dev->struct_mutex);
>  	return ret;
>  }
> @@ -524,6 +526,10 @@ static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
>  static void intel_fbdev_destroy(struct drm_device *dev,
>  				struct intel_fbdev *ifbdev)
>  {
> +	/* We rely on the object-free to release the VMA pinning for
> +	 * the info->screen_base mmaping. Leaking the VMA is simpler than
> +	 * trying to rectify all the possible error paths leading here.
> +	 */
>  
>  	drm_fb_helper_unregister_fbi(&ifbdev->helper);
>  	drm_fb_helper_release_fbi(&ifbdev->helper);
> -- 
> 2.6.2
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Thu, 10 Dec 2015 17:36:04 +0100,
Ville Syrjälä wrote:
> 
> On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> > A long time ago (before 3.14) we relied on a permanent pinning of the
> > ifbdev to lock the fb in place inside the GGTT. However, the
> > introduction of stealing the BIOS framebuffer and reusing its address in
> > the GGTT for the fbdev has muddied waters and we use an inherited fb.
> > However, the inherited fb is only pinned whilst it is active and we no
> > longer have an explicit pin for the info->system_base mmapping used by
> > the fbdev. The result is that after some aperture pressure the fbdev may
> > be evicted, but we continue to write the fbcon into the same GGTT
> > address - overwriting anything else that may be put into that offset.
> > The effect is most pronounced across suspend/resume as
> > intel_fbdev_set_suspend() does a full clear over the whole scanout.
> > 
> > v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> > the BIOS, we do not own the pinned vma (except for the reference we add
> > in this patch for our access via info->screen_base).
> > 
> > v3: Finish balancing the vma pinning for the normal !preallocated case.
> > 
> > v4: Try to simplify the pinning even further.
> > v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: "Goel, Akash" <akash.goel@intel.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > Cc: Lukas Wunner <lukas@wunner.de>
> > Cc: stable@vger.kernel.org
> 
> This seems to have fixed my garbled text+fbcon dead after
> suspend/hibernate issues. Well, only had the patch in for a day or so,
> but so far so good.
> 
> Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Takashi, don't know if you already found this patch, but it's definitely
> something you should try as well.

Great, I'll give this a try.  Thanks!


Takashi
On Sun, Dec 06, 2015 at 09:33:20PM +0100, Lukas Wunner wrote:
> Hi Chris,
> 
> On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> > A long time ago (before 3.14) we relied on a permanent pinning of the
> > ifbdev to lock the fb in place inside the GGTT. However, the
> > introduction of stealing the BIOS framebuffer and reusing its address in
> > the GGTT for the fbdev has muddied waters and we use an inherited fb.
> > However, the inherited fb is only pinned whilst it is active and we no
> > longer have an explicit pin for the info->system_base mmapping used by
> > the fbdev. The result is that after some aperture pressure the fbdev may
> > be evicted, but we continue to write the fbcon into the same GGTT
> > address - overwriting anything else that may be put into that offset.
> > The effect is most pronounced across suspend/resume as
> > intel_fbdev_set_suspend() does a full clear over the whole scanout.
> > 
> > v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> > the BIOS, we do not own the pinned vma (except for the reference we add
> > in this patch for our access via info->screen_base).
> > 
> > v3: Finish balancing the vma pinning for the normal !preallocated case.
> > 
> > v4: Try to simplify the pinning even further.
> > v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
> 
> It's beautiful how little code is needed to fix this. The only remaining
> thing I noticed now while looking over the error paths is that these
> lines in intelfb_alloc() become obsolete with your patch:
> 
>  out:
>  	mutex_unlock(&dev->struct_mutex);
> -	if (!IS_ERR_OR_NULL(fb))
> -		drm_framebuffer_unreference(fb);
>  	return ret;
>  }
> 
> Because at each of the remaining "goto out" in the function,
> fb can be only either an ERR_PTR or NULL.
> 
> Also, further up in the function, the declaration of fb can then be
> changed thus:
> 
> -	struct drm_framebuffer *fb = NULL;
> +	struct drm_framebuffer *fb;
> 
> Kind regards,

Yeah there's room for follow-up polish, but this seems good enough at
least for -fixes.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Lukas, feel like supplying a patch to apply the polish you've spotted on
top?

Thanks, Daniel

> 
> Lukas
> 
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: "Goel, Akash" <akash.goel@intel.com>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > Cc: Lukas Wunner <lukas@wunner.de>
> > Cc: stable@vger.kernel.org
> > ---
> >  drivers/gpu/drm/i915/intel_fbdev.c | 20 +++++++++++++-------
> >  1 file changed, 13 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> > index 7ccde58f8c98..bea75cafc623 100644
> > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > @@ -163,13 +163,6 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
> >  		goto out;
> >  	}
> >  
> > -	/* Flush everything out, we'll be doing GTT only from now on */
> > -	ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL);
> > -	if (ret) {
> > -		DRM_ERROR("failed to pin obj: %d\n", ret);
> > -		goto out;
> > -	}
> > -
> >  	mutex_unlock(&dev->struct_mutex);
> >  
> >  	ifbdev->fb = to_intel_framebuffer(fb);
> > @@ -225,6 +218,14 @@ static int intelfb_create(struct drm_fb_helper *helper,
> >  
> >  	mutex_lock(&dev->struct_mutex);
> >  
> > +	/* Pin the GGTT vma for our access via info->screen_base.
> > +	 * This also validates that any existing fb inherited from the
> > +	 * BIOS is suitable for own access.
> > +	 */
> > +	ret = intel_pin_and_fence_fb_obj(NULL, &ifbdev->fb->base, NULL);
> > +	if (ret)
> > +		goto out_unlock;
> > +
> >  	info = drm_fb_helper_alloc_fbi(helper);
> >  	if (IS_ERR(info)) {
> >  		DRM_ERROR("Failed to allocate fb_info\n");
> > @@ -287,6 +288,7 @@ out_destroy_fbi:
> >  	drm_fb_helper_release_fbi(helper);
> >  out_unpin:
> >  	i915_gem_object_ggtt_unpin(obj);
> > +out_unlock:
> >  	mutex_unlock(&dev->struct_mutex);
> >  	return ret;
> >  }
> > @@ -524,6 +526,10 @@ static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
> >  static void intel_fbdev_destroy(struct drm_device *dev,
> >  				struct intel_fbdev *ifbdev)
> >  {
> > +	/* We rely on the object-free to release the VMA pinning for
> > +	 * the info->screen_base mmaping. Leaking the VMA is simpler than
> > +	 * trying to rectify all the possible error paths leading here.
> > +	 */
> >  
> >  	drm_fb_helper_unregister_fbi(&ifbdev->helper);
> >  	drm_fb_helper_release_fbi(&ifbdev->helper);
> > -- 
> > 2.6.2
> >
On Wed, Dec 16, 2015 at 11:52:17AM +0100, Daniel Vetter wrote:
> On Sun, Dec 06, 2015 at 09:33:20PM +0100, Lukas Wunner wrote:
> > Hi Chris,
> > 
> > On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> > > A long time ago (before 3.14) we relied on a permanent pinning of the
> > > ifbdev to lock the fb in place inside the GGTT. However, the
> > > introduction of stealing the BIOS framebuffer and reusing its address in
> > > the GGTT for the fbdev has muddied waters and we use an inherited fb.
> > > However, the inherited fb is only pinned whilst it is active and we no
> > > longer have an explicit pin for the info->system_base mmapping used by
> > > the fbdev. The result is that after some aperture pressure the fbdev may
> > > be evicted, but we continue to write the fbcon into the same GGTT
> > > address - overwriting anything else that may be put into that offset.
> > > The effect is most pronounced across suspend/resume as
> > > intel_fbdev_set_suspend() does a full clear over the whole scanout.
> > > 
> > > v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> > > the BIOS, we do not own the pinned vma (except for the reference we add
> > > in this patch for our access via info->screen_base).
> > > 
> > > v3: Finish balancing the vma pinning for the normal !preallocated case.
> > > 
> > > v4: Try to simplify the pinning even further.
> > > v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
> > 
> > It's beautiful how little code is needed to fix this. The only remaining
> > thing I noticed now while looking over the error paths is that these
> > lines in intelfb_alloc() become obsolete with your patch:
> > 
> >  out:
> >  	mutex_unlock(&dev->struct_mutex);
> > -	if (!IS_ERR_OR_NULL(fb))
> > -		drm_framebuffer_unreference(fb);
> >  	return ret;
> >  }
> > 
> > Because at each of the remaining "goto out" in the function,
> > fb can be only either an ERR_PTR or NULL.
> > 
> > Also, further up in the function, the declaration of fb can then be
> > changed thus:
> > 
> > -	struct drm_framebuffer *fb = NULL;
> > +	struct drm_framebuffer *fb;
> > 
> > Kind regards,
> 
> Yeah there's room for follow-up polish, but this seems good enough at
> least for -fixes.

I just tested when we started to fail things, and for me it only happens
with 4.4-rc releases (tested with [1]). 4.3.3 OTOH still had the fbcon fb
pinned while X was running.

[1] airlied/drm-fixes 4655a12b81ed ("drm: Don't overwrite UNVERFIED mode status to OK")

> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> Lukas, feel like supplying a patch to apply the polish you've spotted on
> top?
> 
> Thanks, Daniel
> 
> > 
> > Lukas
> > 
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: "Goel, Akash" <akash.goel@intel.com>
> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > Cc: Lukas Wunner <lukas@wunner.de>
> > > Cc: stable@vger.kernel.org
> > > ---
> > >  drivers/gpu/drm/i915/intel_fbdev.c | 20 +++++++++++++-------
> > >  1 file changed, 13 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> > > index 7ccde58f8c98..bea75cafc623 100644
> > > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > > @@ -163,13 +163,6 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
> > >  		goto out;
> > >  	}
> > >  
> > > -	/* Flush everything out, we'll be doing GTT only from now on */
> > > -	ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL);
> > > -	if (ret) {
> > > -		DRM_ERROR("failed to pin obj: %d\n", ret);
> > > -		goto out;
> > > -	}
> > > -
> > >  	mutex_unlock(&dev->struct_mutex);
> > >  
> > >  	ifbdev->fb = to_intel_framebuffer(fb);
> > > @@ -225,6 +218,14 @@ static int intelfb_create(struct drm_fb_helper *helper,
> > >  
> > >  	mutex_lock(&dev->struct_mutex);
> > >  
> > > +	/* Pin the GGTT vma for our access via info->screen_base.
> > > +	 * This also validates that any existing fb inherited from the
> > > +	 * BIOS is suitable for own access.
> > > +	 */
> > > +	ret = intel_pin_and_fence_fb_obj(NULL, &ifbdev->fb->base, NULL);
> > > +	if (ret)
> > > +		goto out_unlock;
> > > +
> > >  	info = drm_fb_helper_alloc_fbi(helper);
> > >  	if (IS_ERR(info)) {
> > >  		DRM_ERROR("Failed to allocate fb_info\n");
> > > @@ -287,6 +288,7 @@ out_destroy_fbi:
> > >  	drm_fb_helper_release_fbi(helper);
> > >  out_unpin:
> > >  	i915_gem_object_ggtt_unpin(obj);
> > > +out_unlock:
> > >  	mutex_unlock(&dev->struct_mutex);
> > >  	return ret;
> > >  }
> > > @@ -524,6 +526,10 @@ static const struct drm_fb_helper_funcs intel_fb_helper_funcs = {
> > >  static void intel_fbdev_destroy(struct drm_device *dev,
> > >  				struct intel_fbdev *ifbdev)
> > >  {
> > > +	/* We rely on the object-free to release the VMA pinning for
> > > +	 * the info->screen_base mmaping. Leaking the VMA is simpler than
> > > +	 * trying to rectify all the possible error paths leading here.
> > > +	 */
> > >  
> > >  	drm_fb_helper_unregister_fbi(&ifbdev->helper);
> > >  	drm_fb_helper_release_fbi(&ifbdev->helper);
> > > -- 
> > > 2.6.2
> > > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
On Thu, Dec 10, 2015 at 05:41:30PM +0100, Takashi Iwai wrote:
> On Thu, 10 Dec 2015 17:36:04 +0100,
> Ville Syrjälä wrote:
> > 
> > On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
> > > A long time ago (before 3.14) we relied on a permanent pinning of the
> > > ifbdev to lock the fb in place inside the GGTT. However, the
> > > introduction of stealing the BIOS framebuffer and reusing its address in
> > > the GGTT for the fbdev has muddied waters and we use an inherited fb.
> > > However, the inherited fb is only pinned whilst it is active and we no
> > > longer have an explicit pin for the info->system_base mmapping used by
> > > the fbdev. The result is that after some aperture pressure the fbdev may
> > > be evicted, but we continue to write the fbcon into the same GGTT
> > > address - overwriting anything else that may be put into that offset.
> > > The effect is most pronounced across suspend/resume as
> > > intel_fbdev_set_suspend() does a full clear over the whole scanout.
> > > 
> > > v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
> > > the BIOS, we do not own the pinned vma (except for the reference we add
> > > in this patch for our access via info->screen_base).
> > > 
> > > v3: Finish balancing the vma pinning for the normal !preallocated case.
> > > 
> > > v4: Try to simplify the pinning even further.
> > > v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Cc: "Goel, Akash" <akash.goel@intel.com>
> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > > Cc: Lukas Wunner <lukas@wunner.de>
> > > Cc: stable@vger.kernel.org
> > 
> > This seems to have fixed my garbled text+fbcon dead after
> > suspend/hibernate issues. Well, only had the patch in for a day or so,
> > but so far so good.
> > 
> > Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Takashi, don't know if you already found this patch, but it's definitely
> > something you should try as well.
> 
> Great, I'll give this a try.  Thanks!

Pulled both patches into dinq. Jani, can you please cherry-pick?

Thanks, Daniel
On Thu, 17 Dec 2015, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Thu, Dec 10, 2015 at 05:41:30PM +0100, Takashi Iwai wrote:
>> On Thu, 10 Dec 2015 17:36:04 +0100,
>> Ville Syrjälä wrote:
>> > 
>> > On Fri, Dec 04, 2015 at 04:05:26PM +0000, Chris Wilson wrote:
>> > > A long time ago (before 3.14) we relied on a permanent pinning of the
>> > > ifbdev to lock the fb in place inside the GGTT. However, the
>> > > introduction of stealing the BIOS framebuffer and reusing its address in
>> > > the GGTT for the fbdev has muddied waters and we use an inherited fb.
>> > > However, the inherited fb is only pinned whilst it is active and we no
>> > > longer have an explicit pin for the info->system_base mmapping used by
>> > > the fbdev. The result is that after some aperture pressure the fbdev may
>> > > be evicted, but we continue to write the fbcon into the same GGTT
>> > > address - overwriting anything else that may be put into that offset.
>> > > The effect is most pronounced across suspend/resume as
>> > > intel_fbdev_set_suspend() does a full clear over the whole scanout.
>> > > 
>> > > v2: Only unpin the intel_fb is we allocate it. If we inherit the fb from
>> > > the BIOS, we do not own the pinned vma (except for the reference we add
>> > > in this patch for our access via info->screen_base).
>> > > 
>> > > v3: Finish balancing the vma pinning for the normal !preallocated case.
>> > > 
>> > > v4: Try to simplify the pinning even further.
>> > > v5: Leak the VMA (cleaned up by object-free) to avoid complicated error paths.
>> > > 
>> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> > > Cc: "Goel, Akash" <akash.goel@intel.com>
>> > > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> > > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
>> > > Cc: Lukas Wunner <lukas@wunner.de>
>> > > Cc: stable@vger.kernel.org
>> > 
>> > This seems to have fixed my garbled text+fbcon dead after
>> > suspend/hibernate issues. Well, only had the patch in for a day or so,
>> > but so far so good.
>> > 
>> > Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> > 
>> > Takashi, don't know if you already found this patch, but it's definitely
>> > something you should try as well.
>> 
>> Great, I'll give this a try.  Thanks!
>
> Pulled both patches into dinq. Jani, can you please cherry-pick?

Picked the first, but I don't have the time to fix the conflicts on the
second one.

BR,
Jani.