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[0/2] drm: Fix atomic helper dirtyfb stalls

Message ID 20210508195641.397198-1-robdclark@gmail.com (mailing list archive)
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Series drm: Fix atomic helper dirtyfb stalls | expand

Message

Rob Clark May 8, 2021, 7:56 p.m. UTC 
From: Rob Clark <robdclark@chromium.org>

Someone on IRC once asked an innocent enough sounding question:  Why
with xf86-video-modesetting is es2gears limited at 120fps.

So I broke out the perfetto tracing mesa MR and took a look.  It turns
out the problem was drm_atomic_helper_dirtyfb(), which would end up
waiting for vblank.. es2gears would rapidly push two frames to Xorg,
which would blit them to screen and in idle hook (I assume) call the
DIRTYFB ioctl.  Which in turn would do an atomic update to flush the
dirty rects, which would stall until the next vblank.  And then the
whole process would repeat.

But this is a bit silly, we only need dirtyfb for command mode DSI
panels.  So lets just skip it otherwise.

Rob Clark (2):
  drm: Fix dirtyfb stalls
  drm/msm/dpu: Wire up needs_dirtyfb

 drivers/gpu/drm/drm_damage_helper.c      |  8 ++++++++
 drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 14 ++++++++++++++
 include/drm/drm_modeset_helper_vtables.h | 14 ++++++++++++++
 3 files changed, 36 insertions(+)