drm/amdgpu: Add empty HDP flush function to JPEG v4.0.3

JPEG v4.0.3 doesn't support HDP flush when RRMT is enabled. Instead,
mmsch fw will do the flush.

This change is necessary for JPEG v4.0.3, no need for backward compatibility
Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Jane Jian <Jane.Jian@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/jpeg_v4_0_3.c

@@ -621,6 +621,13 @@ static uint64_t jpeg_v4_0_3_dec_ring_get_wptr(struct amdgpu_ring *ring)
 			ring->pipe ? (0x40 * ring->pipe - 0xc80) : 0);
 }
 
+static void jpeg_v4_0_3_ring_emit_hdp_flush(struct amdgpu_ring *ring)
+{
+	/* JPEG engine access for HDP flush doesn't work when RRMT is enabled.
+	 * This is a workaround to avoid any HDP flush through JPEG ring.
+	 */
+}
+
 /**
  * jpeg_v4_0_3_dec_ring_set_wptr - set write pointer
  *
@@ -1072,6 +1079,7 @@ static const struct amdgpu_ring_funcs jpeg_v4_0_3_dec_ring_vm_funcs = {
 	.emit_ib = jpeg_v4_0_3_dec_ring_emit_ib,
 	.emit_fence = jpeg_v4_0_3_dec_ring_emit_fence,
 	.emit_vm_flush = jpeg_v4_0_3_dec_ring_emit_vm_flush,
+	.emit_hdp_flush = jpeg_v4_0_3_ring_emit_hdp_flush,
 	.test_ring = amdgpu_jpeg_dec_ring_test_ring,
 	.test_ib = amdgpu_jpeg_dec_ring_test_ib,
 	.insert_nop = jpeg_v4_0_3_dec_ring_nop,