[ Upstream commit e8b0b994c3a5881f0648d53f90435120089c56ad ]
Clear the shadow rptr on suspend. Otherwise, when we resume, we can
have a stale value until CP_WHERE_AM_I executes. If we suspend near
the ringbuffer wraparound point, this can lead to a chicken/egg
situation where we are waiting for ringbuffer space to write the
CP_WHERE_AM_I (or CP_INIT) packet, because we mistakenly believe that
the ringbuffer is full (due to stale rptr value in the shadow).
Fixes errors like:
[drm:adreno_wait_ring [msm]] *ERROR* timeout waiting for space in ringbuffer 0
in the resume path.
Fixes: d3a569fccf ("drm/msm: a6xx: Use WHERE_AM_I for eligible targets")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
3edab64c3e