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drm/msm/a6xx: Clear shadow on suspend

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[ Upstream commit e8b0b994c3 ]

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>
This commit is contained in:
Rob Clark 2020-11-10 10:23:06 -08:00 committed by Greg Kroah-Hartman
parent b38258b693
commit 3edab64c3e
1 changed files with 10 additions and 1 deletions
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11
drivers/gpu/drm/msm/adreno/a6xx_gpu.c
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@ -1045,12 +1045,21 @@ static int a6xx_pm_suspend(struct msm_gpu *gpu)
{
struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
int i, ret;
trace_msm_gpu_suspend(0);
devfreq_suspend_device(gpu->devfreq.devfreq);
return a6xx_gmu_stop(a6xx_gpu);
ret = a6xx_gmu_stop(a6xx_gpu);
if (ret)
return ret;
if (adreno_gpu->base.hw_apriv || a6xx_gpu->has_whereami)
for (i = 0; i < gpu->nr_rings; i++)
a6xx_gpu->shadow[i] = 0;
return 0;
}
static int a6xx_get_timestamp(struct msm_gpu *gpu, uint64_t *value)