[v6,0/6] drm: Add support for atomic async page-flip

Message

André Almeida Aug. 15, 2023, 6:57 p.m. UTC

Hi,

This work from me and Simon adds support for DRM_MODE_PAGE_FLIP_ASYNC through
the atomic API. This feature is already available via the legacy API. The use
case is to be able to present a new frame immediately (or as soon as
possible), even if after missing a vblank. This might result in tearing, but
it's useful when a high framerate is desired, such as for gaming.

Differently from earlier versions, this one refuses to flip if any prop changes
for async flips. The idea is that the fast path of immediate page flips doesn't
play well with modeset changes, so only the fb_id can be changed. The exception
is for mode_id changes, that might be referring to an identical mode (which
would skip a modeset). This is done to make the async API more similar to the
normal API.

Thanks,
	André

- User-space patch: https://github.com/Plagman/gamescope/pull/595
- IGT tests: https://gitlab.freedesktop.org/andrealmeid/igt-gpu-tools/-/tree/atomic_async_page_flip

Changes from v5:
- Add note in the docs that not every redundant attribute will result in no-op,
  some might cause oversynchronization issues.

v5: https://lore.kernel.org/dri-devel/[e-mail]/

Changes from v4:
 - Documentation rewrote by Pekka Paalanen

v4: https://lore.kernel.org/dri-devel/[e-mail]/

Changes from v3:
 - Add new patch to reject prop changes
 - Add a documentation clarifying the KMS atomic state set

v3: https://lore.kernel.org/dri-devel/[e-mail]/

André Almeida (1):
  drm: Refuse to async flip with atomic prop changes

Pekka Paalanen (1):
  drm/doc: Define KMS atomic state set

Simon Ser (4):
  drm: allow DRM_MODE_PAGE_FLIP_ASYNC for atomic commits
  drm: introduce DRM_CAP_ATOMIC_ASYNC_PAGE_FLIP
  drm: introduce drm_mode_config.atomic_async_page_flip_not_supported
  amd/display: indicate support for atomic async page-flips on DC

 Documentation/gpu/drm-uapi.rst                | 44 ++++++++++
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c  |  1 +
 drivers/gpu/drm/drm_atomic_helper.c           |  5 ++
 drivers/gpu/drm/drm_atomic_uapi.c             | 80 +++++++++++++++++--
 drivers/gpu/drm/drm_crtc_internal.h           |  2 +-
 drivers/gpu/drm/drm_ioctl.c                   |  5 ++
 drivers/gpu/drm/drm_mode_object.c             |  2 +-
 .../drm/i915/display/intel_display_driver.c   |  1 +
 drivers/gpu/drm/nouveau/nouveau_display.c     |  1 +
 include/drm/drm_mode_config.h                 | 11 +++
 include/uapi/drm/drm.h                        | 10 ++-
 include/uapi/drm/drm_mode.h                   |  9 +++
 12 files changed, 162 insertions(+), 9 deletions(-)