Eric Anholt writes: > [ Unknown signature status ] > Boris Brezillon writes: > >> On Tue, 06 Jun 2017 13:27:09 -0700 >> Eric Anholt wrote: >> >>> Boris Brezillon writes: >>> >>> > The VC4 KMS driver is implementing its own ->atomic_commit() but there >>> > are a few generic helpers we can use instead of open-coding the logic. >>> > >>> > Signed-off-by: Boris Brezillon >>> > --- >>> > drivers/gpu/drm/vc4/vc4_kms.c | 38 ++++++++++++-------------------------- >>> > 1 file changed, 12 insertions(+), 26 deletions(-) >>> > >>> > diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c >>> > index ad7925a9e0ea..f229abc0991b 100644 >>> > --- a/drivers/gpu/drm/vc4/vc4_kms.c >>> > +++ b/drivers/gpu/drm/vc4/vc4_kms.c >>> > @@ -42,6 +42,10 @@ vc4_atomic_complete_commit(struct vc4_commit *c) >>> > struct drm_device *dev = state->dev; >>> > struct vc4_dev *vc4 = to_vc4_dev(dev); >>> > >>> > + drm_atomic_helper_wait_for_fences(dev, state, false); >>> > + >>> > + drm_atomic_helper_wait_for_dependencies(state); >>> >>> With this wait_for_fences() addition and the reservation stuff that >>> landed, I think we can rip out the "seqno cb" in vc4, and just use >>> drm_atomic_helper_commit() and drm_atomic_hepler_commit_tail(). Do you >>> see anything missing, with that? >> >> I can't tell. I haven't dig enough to understand what this seqno cb was >> used for :-), but Daniel was suggesting the same thing. I'll try to >> better understand what seqno cb does and if it's all safe to get rid of >> it and use the standard helpers. > > The seqno cb was the thing for stalling the modeset until V3D was done > rendering to the planes. The wait_for_fences() does the same thing > using generic dmabuf reservations, so the seqno cb isn't needed any > more. Oh, we've got another user of the seqno cb (async flips), anyway, so we can't delete it quite yet. I've pushed this patch since it's a clear improvement (less code, waits for fences from other devices if any).