drm/amdgpu: fix SDMA suspend/resume on SR-IOV

Update all SDMA versions that support SR-IOV to properly
tear down the ttm buffer functions on suspend.

Tested-by: Bokun Zhang <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c

···
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	int i;
 
-	if (amdgpu_sriov_vf(adev))
+	if (amdgpu_sriov_vf(adev)) {
+		/* disable the scheduler for SDMA */
+		amdgpu_sdma_unset_buffer_funcs_helper(adev);
 		return 0;
+	}
 
 	for (i = 0; i < adev->sdma.num_instances; i++) {
 		amdgpu_irq_put(adev, &adev->sdma.ecc_irq,

drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c

···
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
-	if (amdgpu_sriov_vf(adev))
+	if (amdgpu_sriov_vf(adev)) {
+		/* disable the scheduler for SDMA */
+		amdgpu_sdma_unset_buffer_funcs_helper(adev);
 		return 0;
+	}
 
 	sdma_v5_0_ctx_switch_enable(adev, false);
 	sdma_v5_0_enable(adev, false);

drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c

···
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
-	/*
-	 * Under SRIOV, the VF cannot single-mindedly stop SDMA engine
-	 * However, we still need to clean up the DRM entity
-	 * Therefore, we will re-enable SDMA afterwards.
-	 */
+	if (amdgpu_sriov_vf(adev)) {
+		/* disable the scheduler for SDMA */
+		amdgpu_sdma_unset_buffer_funcs_helper(adev);
+		return 0;
+	}
+
 	sdma_v5_2_ctx_switch_enable(adev, false);
 	sdma_v5_2_enable(adev, false);
-
-	if (amdgpu_sriov_vf(adev)) {
-		sdma_v5_2_enable(adev, true);
-		sdma_v5_2_ctx_switch_enable(adev, true);
-	}
 
 	return 0;
 }

drivers/gpu/drm/amd/amdgpu/sdma_v6_0.c

···
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
-	if (amdgpu_sriov_vf(adev))
+	if (amdgpu_sriov_vf(adev)) {
+		/* disable the scheduler for SDMA */
+		amdgpu_sdma_unset_buffer_funcs_helper(adev);
 		return 0;
+	}
 
 	sdma_v6_0_ctx_switch_enable(adev, false);
 	sdma_v6_0_enable(adev, false);