Am Mittwoch, 13. Januar 2016, 12:53:34 schrieb John Keeping:
As commented in drm_atomic_helper_wait_for_vblanks(), userspace relies on cursor ioctls being unsynced. Converting the rockchip driver to atomic has significantly impacted cursor performance by making every cursor update wait for vblank.
By skipping the vblank sync when the framebuffer has not changed (as is done in drm_atomic_helper_wait_for_vblanks()) we can avoid this for the common case of moving the cursor and only need to delay the cursor ioctl when the cursor icon changes.
I originally inserted a check on legacy_cursor_update as well, but that caused a storm of iommu page faults. I didn't investigate the cause of those since this change gives enough of a performance improvement for my use case.
This is RFC because of that and because the framebuffer_changed() function is copied from drm_atomic_helper.c as a quick way to test the result.
Signed-off-by: John Keeping john@metanate.com
I've seen the effects now as well after making the atomic parts work on in my devtree - i.e. sluggish cursor movements.
This patch fixes that issue, so at least: Tested-by: Heiko Stuebner heiko@sntech.de
Right now I still see flickering on animated cursors though (like ones used by KDE), that wasn't present before.
Heiko