This is a note to let you know that I've just added the patch titled
drm/vmwgfx: Don't memcmp equivalent pointers
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-vmwgfx-don-t-memcmp-equivalent-pointers.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ceddcab7a0ab352dc17fe3c4204a6d723588450f
Author: Ian Forbes <ian.forbes@xxxxxxxxxxxx>
Date: Thu Mar 28 14:07:16 2024 -0500
drm/vmwgfx: Don't memcmp equivalent pointers
[ Upstream commit 5703fc058efdafcdd6b70776ee562478f0753acb ]
These pointers are frequently the same and memcmp does not compare the
pointers before comparing their contents so this was wasting cycles
comparing 16 KiB of memory which will always be equal.
Fixes: bb6780aa5a1d ("drm/vmwgfx: Diff cursors when using cmds")
Signed-off-by: Ian Forbes <ian.forbes@xxxxxxxxxxxx>
Signed-off-by: Zack Rusin <zack.rusin@xxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240328190716.27367-1-ian.forbes@xxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 93e2a27daed0c..08f2470edab27 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -216,7 +216,7 @@ static bool vmw_du_cursor_plane_has_changed(struct vmw_plane_state *old_vps,
new_image = vmw_du_cursor_plane_acquire_image(new_vps);
changed = false;
- if (old_image && new_image)
+ if (old_image && new_image && old_image != new_image)
changed = memcmp(old_image, new_image, size) != 0;
return changed;
