This is one of several patchset s to improve fb deferred I/O and DRM's use of it. The patches fix several problems with the current helpers and add some easy improvements.
Deferred I/O tracks dirty pages of the screen buffer, from which DRM calculates a bounding box of the damaged area. Patches 1 and 2 resolve bugs in the computation. Specifically, it makes the damage handling work with overallocation and panning enabled.
Patches 3 to 5 add an easy performance improvement. Instead of damaging the whole viewport after a write operation, only damage the written area. For large writes the area consists of multiple scanlines, for small writes the area might consist of only a few pixels on a single scanline. Write operations now also work correctly with overallocation and panning enabled.
v2: * rename memory-to-clip helper (Javier)
Thomas Zimmermann (5): drm/fb-helper: Fix clip rectangle height drm/fb-helper: Fix vertical damage clipping drm/fb-helper: Calculate damaged area in separate helper drm/fb-helper: Clip damage area to written memory range drm/fb-helper: Clip damage area horizontally
drivers/gpu/drm/drm_fb_helper.c | 69 ++++++++++++++++++++++++++------- 1 file changed, 54 insertions(+), 15 deletions(-)