drm/amd/sriov skip vcn powergating and dec_ring_test

1.Skip decode_ring test in VF, because VCN in SRIOV does not
support direct register read/write.

2.Skip powergating configuration in hw fini because
VCN3.0 SRIOV doesn't support powergating.

V2: delete unneccessary white lines and refine implementation.
Signed-off-by: Jack Zhang <Jack.Zhang1@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -421,6 +421,10 @@ int amdgpu_vcn_dec_ring_test_ring(struct amdgpu_ring *ring)
 	unsigned i;
 	int r;
 
+	/* VCN in SRIOV does not support direct register read/write */
+	if (amdgpu_sriov_vf(adev))
+		return 0;
+
 	WREG32(adev->vcn.inst[ring->me].external.scratch9, 0xCAFEDEAD);
 	r = amdgpu_ring_alloc(ring, 3);
 	if (r)

drivers/gpu/drm/amd/amdgpu/vcn_v3_0.c

@@ -354,11 +354,13 @@ static int vcn_v3_0_hw_fini(void *handle)
 
 		ring = &adev->vcn.inst[i].ring_dec;
 
+		if (!amdgpu_sriov_vf(adev)) {
 			if ((adev->pg_flags & AMD_PG_SUPPORT_VCN_DPG) ||
 					(adev->vcn.cur_state != AMD_PG_STATE_GATE &&
-			RREG32_SOC15(VCN, i, mmUVD_STATUS)))
+					 RREG32_SOC15(VCN, i, mmUVD_STATUS))) {
 				vcn_v3_0_set_powergating_state(adev, AMD_PG_STATE_GATE);
-
+			}
+		}
 		ring->sched.ready = false;
 
 		for (j = 0; j < adev->vcn.num_enc_rings; ++j) {
@@ -1861,6 +1863,15 @@ static int vcn_v3_0_set_powergating_state(void *handle,
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 	int ret;
 
+	/* for SRIOV, guest should not control VCN Power-gating
+	 * MMSCH FW should control Power-gating and clock-gating
+	 * guest should avoid touching CGC and PG
+	 */
+	if (amdgpu_sriov_vf(adev)) {
+		adev->vcn.cur_state = AMD_PG_STATE_UNGATE;
+		return 0;
+	}
+
 	if(state == adev->vcn.cur_state)
 		return 0;