From: Rob Clark <robdcl...@chromium.org>

Prior to the last commit, this could result in setting the GPU
written fence value back to an older value, if we had missed
updating completed_fence prior to suspend.  This was mostly
harmless as the GPU would eventually overwrite it again with
the correct value.  But we should just not do this.  Instead
just leave a sanity check that the fence looks plausible (in
case the GPU scribbled on memory).

Reported-by: Steev Klimaszewski <st...@kali.org>
Fixes: 95d1deb02a9c ("drm/msm/gem: Add fenced vma unpin")
Signed-off-by: Rob Clark <robdcl...@chromium.org>
Tested-by: Steev Klimaszewski <st...@kali.org>
---
 drivers/gpu/drm/msm/adreno/adreno_gpu.c | 11 ++++++++---
 drivers/gpu/drm/msm/msm_gpu.c           |  2 +-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c 
b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
index f944b69e2a25..efe9840e28fa 100644
--- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
@@ -498,10 +498,15 @@ int adreno_hw_init(struct msm_gpu *gpu)
 
                ring->cur = ring->start;
                ring->next = ring->start;
-
-               /* reset completed fence seqno: */
-               ring->memptrs->fence = ring->fctx->completed_fence;
                ring->memptrs->rptr = 0;
+
+               /* Detect and clean up an impossible fence, ie. if GPU managed
+                * to scribble something invalid, we don't want that to confuse
+                * us into mistakingly believing that submits have completed.
+                */
+               if (fence_before(ring->fctx->last_fence, ring->memptrs->fence)) 
{
+                       ring->memptrs->fence = ring->fctx->last_fence;
+               }
        }
 
        return 0;
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index cedc88cf8083..c8cd9bfa3eeb 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -418,7 +418,7 @@ static void recover_worker(struct kthread_work *work)
                 * one more to clear the faulting submit
                 */
                if (ring == cur_ring)
-                       fence++;
+                       ring->memptrs->fence = ++fence;
 
                msm_update_fence(ring->fctx, fence);
        }
-- 
2.36.1

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