[3/4] drm/i915: refactor i915_gem_object_pin_map()

Submitted by Dave Gordon on April 22, 2016, 3:06 p.m.

Details

Message ID 1461337609-31130-4-git-send-email-david.s.gordon@intel.com
State New
Headers show
Series "Series without cover letter" ( rev: 1 ) in Intel GFX - Try Bot

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Commit Message

Dave Gordon April 22, 2016, 3:06 p.m.
The recently-added i915_gem_object_pin_map() can be further optimised
for "small" objects. To facilitate this, and simplify the error paths
before adding the new code, this patch pulls out the "mapping" part of
the operation (involving local allocations which must be undone before
return) into its own subfunction.

The next patch will then insert the new optimisation into the middle of
the now-separated subfunction.

This reorganisation will probably not affect the generated code, as the
compiler will most likely inline it anyway, but it makes the logical
structure a bit clearer and easier to modify.

v2:
    Restructure loop-over-pages & error check (Chris Wilson)

v3:
    Use new nicer SGL page-range iterator (Dave Gordon)
    Add page count to debug messages (Chris Wilson)
    Convert WARN_ON() to GEM_BUG_ON()

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c | 59 ++++++++++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 21 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 17e061f..a43f204 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2386,6 +2386,43 @@  static void i915_gem_object_free_mmap_offset(struct drm_i915_gem_object *obj)
 	return 0;
 }
 
+/* The 'mapping' part of i915_gem_object_pin_map() below */
+static void *i915_gem_object_map(const struct drm_i915_gem_object *obj)
+{
+	unsigned long n_pages = obj->base.size >> PAGE_SHIFT;
+	struct sg_table *sgt = obj->pages;
+	struct sg_page_iter sg_iter;
+	struct page **pages;
+	unsigned long i = 0;
+	void *addr = NULL;
+
+	/* A single page can always be kmapped */
+	if (n_pages == 1)
+		return kmap(sg_page(sgt->sgl));
+
+	pages = drm_malloc_gfp(n_pages, sizeof(*pages), GFP_TEMPORARY);
+	if (pages == NULL) {
+		DRM_DEBUG_DRIVER("Failed to get space for %lu pointers\n",
+				 n_pages);
+		return NULL;
+	}
+
+	for_each_sgt_page_range(&sg_iter, sgt, 0, n_pages)
+		pages[i++] = sg_page_iter_page(&sg_iter);
+
+	/* Check that we have the expected number of pages */
+	GEM_BUG_ON(i != n_pages);
+
+	addr = vmap(pages, n_pages, 0, PAGE_KERNEL);
+	if (addr == NULL)
+		DRM_DEBUG_DRIVER("Failed to vmap %lu pages\n", n_pages);
+
+	drm_free_large(pages);
+
+	return addr;
+}
+
+/* get, pin, and map the pages of the object into kernel space */
 void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj)
 {
 	int ret;
@@ -2399,27 +2436,7 @@  void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj)
 	i915_gem_object_pin_pages(obj);
 
 	if (obj->mapping == NULL) {
-		struct page **pages;
-
-		pages = NULL;
-		if (obj->base.size == PAGE_SIZE)
-			obj->mapping = kmap(sg_page(obj->pages->sgl));
-		else
-			pages = drm_malloc_gfp(obj->base.size >> PAGE_SHIFT,
-					       sizeof(*pages),
-					       GFP_TEMPORARY);
-		if (pages != NULL) {
-			struct sg_page_iter sg_iter;
-			int n;
-
-			n = 0;
-			for_each_sg_page(obj->pages->sgl, &sg_iter,
-					 obj->pages->nents, 0)
-				pages[n++] = sg_page_iter_page(&sg_iter);
-
-			obj->mapping = vmap(pages, n, 0, PAGE_KERNEL);
-			drm_free_large(pages);
-		}
+		obj->mapping = i915_gem_object_map(obj);
 		if (obj->mapping == NULL) {
 			i915_gem_object_unpin_pages(obj);
 			return ERR_PTR(-ENOMEM);