drm/amdgpu: Fix dummy_read_page overlapping mappings

Use the dma_map_page_attrs() with DMA_ATTR_SKIP_CPU_SYNC
attribute setting to handle the dummy page overlapping
mappings.

Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c

@@ -78,8 +78,9 @@ static int amdgpu_gart_dummy_page_init(struct amdgpu_device *adev)
 
 	if (adev->dummy_page_addr)
 		return 0;
-	adev->dummy_page_addr = dma_map_page(&adev->pdev->dev, dummy_page, 0,
-					     PAGE_SIZE, DMA_BIDIRECTIONAL);
+	adev->dummy_page_addr = dma_map_page_attrs(&adev->pdev->dev, dummy_page, 0,
+							PAGE_SIZE, DMA_BIDIRECTIONAL,
+							DMA_ATTR_SKIP_CPU_SYNC);
 	if (dma_mapping_error(&adev->pdev->dev, adev->dummy_page_addr)) {
 		dev_err(&adev->pdev->dev, "Failed to DMA MAP the dummy page\n");
 		adev->dummy_page_addr = 0;
@@ -99,8 +100,9 @@ void amdgpu_gart_dummy_page_fini(struct amdgpu_device *adev)
 {
 	if (!adev->dummy_page_addr)
 		return;
-	dma_unmap_page(&adev->pdev->dev, adev->dummy_page_addr, PAGE_SIZE,
-		       DMA_BIDIRECTIONAL);
+	dma_unmap_page_attrs(&adev->pdev->dev, adev->dummy_page_addr, PAGE_SIZE,
+				DMA_BIDIRECTIONAL,
+				DMA_ATTR_SKIP_CPU_SYNC);
 	adev->dummy_page_addr = 0;
 }