From: Michel D?nzer <michel.daen...@amd.com>

This fixes a ring test failure reported on a Kabini system which was
triggered by write-combined CPU mappings of the ring buffers.

Reported-and-Tested-by: Will Trives <renevant at internode.on.net>
Signed-off-by: Michel D?nzer <michel.daenzer at amd.com>
---
 drivers/gpu/drm/radeon/radeon_ring.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_ring.c 
b/drivers/gpu/drm/radeon/radeon_ring.c
index 5b4e0cf..6dff529 100644
--- a/drivers/gpu/drm/radeon/radeon_ring.c
+++ b/drivers/gpu/drm/radeon/radeon_ring.c
@@ -193,6 +193,10 @@ void radeon_ring_commit(struct radeon_device *rdev, struct 
radeon_ring *ring)
                radeon_ring_write(ring, ring->nop);
        }
        mb();
+       /* This is necessary to prevent ring test failures on some systems
+        * with write-combined CPU mappings of the ring buffers
+        */
+       (void)ring->ring[ring->wptr];
        /* If we are emitting the HDP flush via MMIO, we need to do it after
         * all CPU writes to VRAM finished.
         */
-- 
2.0.1

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