[RFC v2 0/7] drm: asynchronous atomic plane update

[Gustavo Padovan]

From: Gustavo Padovan <gustavo.padovan at collabora.com>

Hi,

Second take of Asynchronous Plane Updates over Atomic. Here I looked
to msm, vc4 and i915 to identify a common pattern to create atomic helpers
for async updates. So in patch 1 drm_atomic_async_check() and
drm_atomic_helper_async_commit() are introduced along with driver's plane hooks:
->atomic_async_check() and ->atomic_async_commit().

For now we only support async update for one plane at a time. Also the async
update can't modify the CRTC so no modesets are allowed.

Then the other patches add support for it in the drivers. I did virtio mostly
for testing. i915 have been converted and I've been using it without any
problem. IGT tests seems to be fine, but there are somewhat random failures
with or without the async update changes. msm and vc4 are only compile-tested.
So I think this needs more testing

I started IGT changes to test the Atomic IOCTL with the new flag:

https://git.collabora.com/cgit/user/padovan/intel-gpu-tools.git/

v2:

Apart from all comments on v1 one extra change I made was to remove the
constraint of only updating the plane if the queued state didn't touch
that plane. I believe it was a too cautious of a change, furthermore this
constraint was affecting throughput negatively on i915.

TODO

 - improve i-g-t tests where needed
 - support async page flips (that can be done after uptreaming this part)
 - figure out what to do for hw that do not update the plane until the next
 vblank. Maybe wait and see what they do and them extract helpers?

Comments are welcome!

Gustavo Padovan (7):
  drm/atomic: initial support for asynchronous plane update
  drm/virtio: support async cursor updates
  drm/i915: update cursors asynchronously through atomic
  drm/i915: remove intel_cursor_plane_funcs
  drm/msm: update cursors asynchronously through atomic
  drm/msm: remove mdp5_cursor_plane_funcs
  drm/vc4: update cursors asynchronously through atomic

 drivers/gpu/drm/drm_atomic.c              |  50 ++++++++++
 drivers/gpu/drm/drm_atomic_helper.c       |  48 +++++++++
 drivers/gpu/drm/i915/intel_atomic_plane.c |  52 ++++++++++
 drivers/gpu/drm/i915/intel_display.c      | 158 ++++-------------------------
 drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c | 161 ++++++++++--------------------
 drivers/gpu/drm/vc4/vc4_plane.c           |  94 +++++------------
 drivers/gpu/drm/virtio/virtgpu_plane.c    |  42 ++++++++
 include/drm/drm_atomic.h                  |   2 +
 include/drm/drm_atomic_helper.h           |   2 +
 include/drm/drm_modeset_helper_vtables.h  |  45 +++++++++
 include/uapi/drm/drm_mode.h               |   4 +-
 11 files changed, 343 insertions(+), 315 deletions(-)

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2.9.3