drm/amdgpu/{uvd,vcn}: fetch ring's read_ptr after alloc

[What]
readptr read always returns zero, since most likely
these blocks are either power or clock gated.

[How]
fetch rptr after amdgpu_ring_alloc() which informs
the power management code that the block is about to be
used and hence the gating is turned off.
Signed-off-by: Louis Li <Ching-shih.Li@amd.com>
Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

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

@@ -594,7 +594,7 @@ int amdgpu_vcn_dec_ring_test_ib(struct amdgpu_ring *ring, long timeout)
 int amdgpu_vcn_enc_ring_test_ring(struct amdgpu_ring *ring)
 {
 	struct amdgpu_device *adev = ring->adev;
-	uint32_t rptr = amdgpu_ring_get_rptr(ring);
+	uint32_t rptr;
 	unsigned i;
 	int r;
 
@@ -602,6 +602,8 @@ int amdgpu_vcn_enc_ring_test_ring(struct amdgpu_ring *ring)
 	if (r)
 		return r;
 
+	rptr = amdgpu_ring_get_rptr(ring);
+
 	amdgpu_ring_write(ring, VCN_ENC_CMD_END);
 	amdgpu_ring_commit(ring);
 

drivers/gpu/drm/amd/amdgpu/uvd_v6_0.c

@@ -170,13 +170,16 @@ static void uvd_v6_0_enc_ring_set_wptr(struct amdgpu_ring *ring)
 static int uvd_v6_0_enc_ring_test_ring(struct amdgpu_ring *ring)
 {
 	struct amdgpu_device *adev = ring->adev;
-	uint32_t rptr = amdgpu_ring_get_rptr(ring);
+	uint32_t rptr;
 	unsigned i;
 	int r;
 
 	r = amdgpu_ring_alloc(ring, 16);
 	if (r)
 		return r;
+
+	rptr = amdgpu_ring_get_rptr(ring);
+
 	amdgpu_ring_write(ring, HEVC_ENC_CMD_END);
 	amdgpu_ring_commit(ring);
 

drivers/gpu/drm/amd/amdgpu/uvd_v7_0.c

@@ -175,7 +175,7 @@ static void uvd_v7_0_enc_ring_set_wptr(struct amdgpu_ring *ring)
 static int uvd_v7_0_enc_ring_test_ring(struct amdgpu_ring *ring)
 {
 	struct amdgpu_device *adev = ring->adev;
-	uint32_t rptr = amdgpu_ring_get_rptr(ring);
+	uint32_t rptr;
 	unsigned i;
 	int r;
 
@@ -185,6 +185,9 @@ static int uvd_v7_0_enc_ring_test_ring(struct amdgpu_ring *ring)
 	r = amdgpu_ring_alloc(ring, 16);
 	if (r)
 		return r;
+
+	rptr = amdgpu_ring_get_rptr(ring);
+
 	amdgpu_ring_write(ring, HEVC_ENC_CMD_END);
 	amdgpu_ring_commit(ring);