diff mbox series

[v2,01/12] drm/vram: Support top-down placement flag

Message ID 20190923172753.26593-2-tzimmermann@suse.de (mailing list archive)
State New, archived
Headers show
Series drm/ast/mgag200: Place cursor BOs at VRAM high-end | expand

Commit Message

Thomas Zimmermann Sept. 23, 2019, 5:27 p.m. UTC 
Pinning lots of small buffer objects, such as cursors or sprites, to video
memory can lead to fragmentation, which is a problem for devices with only
a small amount of memory. As a result, framebuffer images might not get
pinned, even though there's enough space available overall.

The flag DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks buffer objects to be pinned at
the high end of video memory. This leaves contiguous space available at
the memory's low end.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 14 ++++++++++----
 include/drm/drm_gem_vram_helper.h     |  1 +
 2 files changed, 11 insertions(+), 4 deletions(-)

Comments

Gerd Hoffmann Sept. 24, 2019, 7:18 a.m. UTC | #1 
Hi,

> + * object to be pinned at the high end of the memory region. Set this
> + * flag to avoid memory fragmentation.

That is confusing, sounds like the flag should be set on all objects
which is not correct.  The description from the cover letter is better.

Otherwise the patch is fine, so with that fixed:
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

cheers,
  Gerd
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 49588de88959..91baf3f279f1 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -58,6 +58,7 @@  static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo,
 {
 	unsigned int i;
 	unsigned int c = 0;
+	u32 invariant_flags = pl_flag & TTM_PL_FLAG_TOPDOWN;
 
 	gbo->placement.placement = gbo->placements;
 	gbo->placement.busy_placement = gbo->placements;
@@ -65,15 +66,18 @@  static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo,
 	if (pl_flag & TTM_PL_FLAG_VRAM)
 		gbo->placements[c++].flags = TTM_PL_FLAG_WC |
 					     TTM_PL_FLAG_UNCACHED |
-					     TTM_PL_FLAG_VRAM;
+					     TTM_PL_FLAG_VRAM |
+					     invariant_flags;
 
 	if (pl_flag & TTM_PL_FLAG_SYSTEM)
 		gbo->placements[c++].flags = TTM_PL_MASK_CACHING |
-					     TTM_PL_FLAG_SYSTEM;
+					     TTM_PL_FLAG_SYSTEM |
+					     invariant_flags;
 
 	if (!c)
 		gbo->placements[c++].flags = TTM_PL_MASK_CACHING |
-					     TTM_PL_FLAG_SYSTEM;
+					     TTM_PL_FLAG_SYSTEM |
+					     invariant_flags;
 
 	gbo->placement.num_placement = c;
 	gbo->placement.num_busy_placement = c;
@@ -236,7 +240,9 @@  static int drm_gem_vram_pin_locked(struct drm_gem_vram_object *gbo,
  * a memory region. A pinned buffer object has to be unpinned before
  * it can be pinned to another region. If the pl_flag argument is 0,
  * the buffer is pinned at its current location (video RAM or system
- * memory).
+ * memory). The modifier DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks the buffer
+ * object to be pinned at the high end of the memory region. Set this
+ * flag to avoid memory fragmentation.
  *
  * Returns:
  * 0 on success, or
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h
index 418eb1122861..354a9cd358a3 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -19,6 +19,7 @@  struct vm_area_struct;
 
 #define DRM_GEM_VRAM_PL_FLAG_VRAM	TTM_PL_FLAG_VRAM
 #define DRM_GEM_VRAM_PL_FLAG_SYSTEM	TTM_PL_FLAG_SYSTEM
+#define DRM_GEM_VRAM_PL_FLAG_TOPDOWN	TTM_PL_FLAG_TOPDOWN
 
 /*
  * Buffer-object helpers