media: videobuf2: check ->synced flag in prepare() and finish()

This simplifies the code a tiny bit and let's us to avoid
unneeded ->prepare()/->finish() calls.
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/common/videobuf2/videobuf2-core.c

@@ -304,6 +304,9 @@ static void __vb2_buf_mem_prepare(struct vb2_buffer *vb)
 {
 	unsigned int plane;
 
+	if (vb->synced)
+		return;
+
 	if (vb->need_cache_sync_on_prepare) {
 		for (plane = 0; plane < vb->num_planes; ++plane)
 			call_void_memop(vb, prepare,
@@ -320,6 +323,9 @@ static void __vb2_buf_mem_finish(struct vb2_buffer *vb)
 {
 	unsigned int plane;
 
+	if (!vb->synced)
+		return;
+
 	if (vb->need_cache_sync_on_finish) {
 		for (plane = 0; plane < vb->num_planes; ++plane)
 			call_void_memop(vb, finish,
@@ -1999,7 +2005,6 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
 				call_void_vb_qop(vb, buf_request_complete, vb);
 		}
 
-		if (vb->synced)
 		__vb2_buf_mem_finish(vb);
 
 		if (vb->prepared) {