[PATCH v1] drm/amdgpu: implement workaround for sdma dcc corruption

[Pierre-Eric Pelloux-Prayer]

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 <pierre-eric.pelloux-prayer@xxxxxxx>
---
 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