media: s5p-g2d: Implement wait_prepare and wait_finish

This driver is currently specifying a vb2_queue lock,
which means it straightforward to implement wait_prepare
and wait_finish.

Having these callbacks releases the queue lock while blocking,
which improves latency by allowing for example streamoff
or qbuf operations while waiting in dqbuf.

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/s5p-g2d/g2d.c

@@ -142,6 +142,8 @@ static const struct vb2_ops g2d_qops = {
 	.queue_setup	= g2d_queue_setup,
 	.buf_prepare	= g2d_buf_prepare,
 	.buf_queue	= g2d_buf_queue,
+	.wait_prepare	= vb2_ops_wait_prepare,
+	.wait_finish	= vb2_ops_wait_finish,
 };
 
 static int queue_init(void *priv, struct vb2_queue *src_vq,