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 <[e-mail]>
Signed-off-by: Shirish S <[e-mail]>
Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
Cc: [e-mail]

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

···
 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;
 
 	r = amdgpu_ring_alloc(ring, 16);
 	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

···
 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

···
 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;
 
···
 	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);