This is a note to let you know that I've just added the patch titled drm/msm: Fix races managing the OOB state for timestamp vs timestamps. to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-msm-fix-races-managing-the-oob-state-for-timesta.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f50bd13924b3c51f25f9a350da6c94b3f06b3620 Author: Eric Anholt <eric@xxxxxxxxxx> Date: Thu Jan 28 13:03:31 2021 -0800 drm/msm: Fix races managing the OOB state for timestamp vs timestamps. [ Upstream commit 5f98b33b04c02c0d9088c7486c59d058696782f9 ] Now that we're not racing with GPU setup, also fix races of timestamps against other timestamps. In freedreno CI, we were seeing this path trigger timeouts on setting the GMU bit, producing: [drm:_a6xx_gmu_set_oob] *ERROR* Timeout waiting for GMU OOB set GPU_SET: 0x0 and this triggered especially on the first set of tests right after boot (it's probably easier to lose the race than one might think, given that we start many tests in parallel, and waiting for NFS to page in code probably means that lots of tests hit the same point of screen init at the same time). As of this patch, the message seems to have completely gone away. Signed-off-by: Eric Anholt <eric@xxxxxxxxxx> Fixes: 4b565ca5a2cb ("drm/msm: Add A6XX device support") Reviewed-by: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c index 2dc6b342cf9b5..0366419d8bfed 100644 --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c @@ -1169,6 +1169,9 @@ static int a6xx_get_timestamp(struct msm_gpu *gpu, uint64_t *value) { struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu); struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu); + static DEFINE_MUTEX(perfcounter_oob); + + mutex_lock(&perfcounter_oob); /* Force the GPU power on so we can read this register */ a6xx_gmu_set_oob(&a6xx_gpu->gmu, GMU_OOB_PERFCOUNTER_SET); @@ -1177,6 +1180,7 @@ static int a6xx_get_timestamp(struct msm_gpu *gpu, uint64_t *value) REG_A6XX_RBBM_PERFCTR_CP_0_HI); a6xx_gmu_clear_oob(&a6xx_gpu->gmu, GMU_OOB_PERFCOUNTER_SET); + mutex_unlock(&perfcounter_oob); return 0; }