[PATCH v2 3/8] drm/vc4: Use wait_for_flip_done() instead of wait_for_vblanks()

[Eric Anholt]

Boris Brezillon <boris.brezillon at bootlin.com> writes:

> drm_atomic_helper_wait_for_vblanks() assumes the CRTC will continuously
> generate VBLANK events and the vblank counter will keep increasing.
> While this work for a regular pipeline, it doesn't when you have the
> CRTC is feeding the transposer block, because this block works in
> oneshot mode, and, by the time we reach
> drm_atomic_helper_wait_for_vblanks() the only VBLANK event might have
> already been sent and the VBLANK counter will stay unchanged, thus
> triggering a timeout.
>
> Luckily, we can replace the drm_atomic_helper_wait_for_vblanks() call
> by drm_atomic_helper_wait_for_flip_done() because the only thing we
> want to check when calling drm_atomic_helper_wait_for_vblanks() from
> vc4_atomic_complete_commit() is that new FBs are in use and the old
> ones can be safely released.
>
> Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>

Reviewed-by: Eric Anholt <eric at anholt.net>
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