Enable FB_DAMAGE_CLIPS with simpledrm for improved performance and/or less overhead. With this in place, add support for virtual screens (i.e., framebuffers that are larger than the display resolution). This also enables fbdev panning and page flipping.
After the discussion and bug fixing wrt to fbdev overallocation, I decided to add full support for this to simpledrm. Patches #1 to #5 change the format-helper functions accordingly. Destination buffers are now clipped by the caller and all functions support a similar feature set. This has some fallout in various drivers.
Patch #6 change fbdev emulation to support overallocation with shadow buffers, even if the hardware buffer would be too small.
Patch #7 and #8 update simpledrm to enable damage clipping and virtual screen sizes. Both features go hand in hand, sort of. For shadow- buffered planes, the DRM framebuffer lives in system memory. So the maximum size of the virtual screen is somewhat arbitrary. We add two constants for resonable maximum width and height of 4096 each.
Patch #9 adds documentation and a TODO item.
Tested with simpledrm. I also ran the recently posted fbdev panning tests to make sure that the fbdev overallocation works correctly. [1]
v2: * add missing docs (Sam) * return unsigned int from drm_fb_clip_offset() (Sam, Noralf) * fix OOB access in drm_fb_xrgb8888_to_gray8() (Noralf)
[1] https://lists.freedesktop.org/archives/igt-dev/2021-October/036642.html
Thomas Zimmermann (9): drm/format-helper: Export drm_fb_clip_offset() drm/format-helper: Rework format-helper memcpy functions drm/format-helper: Add destination-buffer pitch to drm_fb_swab() drm/format-helper: Rework format-helper conversion functions drm/format-helper: Streamline blit-helper interface drm/fb-helper: Allocate shadow buffer of surface height drm/simpledrm: Enable FB_DAMAGE_CLIPS property drm/simpledrm: Support virtual screen sizes drm: Clarify semantics of struct drm_mode_config.{min,max}_{width,height}
Documentation/gpu/todo.rst | 15 ++ drivers/gpu/drm/drm_fb_helper.c | 2 +- drivers/gpu/drm/drm_format_helper.c | 247 ++++++++++---------- drivers/gpu/drm/drm_mipi_dbi.c | 6 +- drivers/gpu/drm/gud/gud_pipe.c | 14 +- drivers/gpu/drm/hyperv/hyperv_drm_modeset.c | 5 +- drivers/gpu/drm/mgag200/mgag200_mode.c | 4 +- drivers/gpu/drm/tiny/cirrus.c | 24 +- drivers/gpu/drm/tiny/repaper.c | 2 +- drivers/gpu/drm/tiny/simpledrm.c | 41 +++- drivers/gpu/drm/tiny/st7586.c | 2 +- include/drm/drm_format_helper.h | 58 ++--- include/drm/drm_gem_atomic_helper.h | 18 ++ include/drm/drm_mode_config.h | 13 ++ 14 files changed, 264 insertions(+), 187 deletions(-)
-- 2.33.1