For unknown reasons, on gfx12 using multiple entities can causes
random corruption of BOs with DCC.
This workaround seems to prevent the issue until the root cause
is understood and fixed.

Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5663
Fixes: 3a6f6eeb3db5 ("drm/amdgpu: give ttm entities access to all the sdma 
scheds")
Signed-off-by: Pierre-Eric Pelloux-Prayer <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 3d620ec2937f..a826e091ea58 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -2392,6 +2392,11 @@ void amdgpu_ttm_enable_buffer_funcs(struct amdgpu_device 
*adev)
 
        num_clear_entities = MIN(adev->mman.num_buffer_funcs_scheds, 
TTM_NUM_MOVE_FENCES);
        num_move_entities = MIN(adev->mman.num_buffer_funcs_scheds, 
TTM_NUM_MOVE_FENCES);
+        /* TODO: workaround for DCC corruption when moving BOs from multiple 
queues at
+         * the same time: use a single queue until the root cause is 
identified and fixed.
+         */
+       if (IP_VERSION_MAJ(amdgpu_ip_version(adev, SDMA0_HWIP, 0)) == 7)
+               num_move_entities = 1;
 
        adev->mman.clear_entities = kcalloc(num_clear_entities,
                                                sizeof(struct 
amdgpu_ttm_buffer_entity),
-- 
2.43.0

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