[media] coda: set allow_zero_bytesused flag for vb2_queue_init

The coda driver interprets a buffer with bytesused equal to 0 as a special
case indicating end-of-stream. After vb2: fix bytesused == 0 handling
(8a75ffb8) patch videobuf2 modified the value of bytesused if it was 0.
The allow_zero_bytesused flag was added to videobuf2 to keep
backward compatibility.
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/coda/coda-common.c

@@ -1541,6 +1541,13 @@ static int coda_queue_init(struct coda_ctx *ctx, struct vb2_queue *vq)
 	vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);
 	vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
 	vq->lock = &ctx->dev->dev_mutex;
+	/* One way to indicate end-of-stream for coda is to set the
+	 * bytesused == 0. However by default videobuf2 handles bytesused
+	 * equal to 0 as a special case and changes its value to the size
+	 * of the buffer. Set the allow_zero_bytesused flag, so
+	 * that videobuf2 will keep the value of bytesused intact.
+	 */
+	vq->allow_zero_bytesused = 1;
 
 	return vb2_queue_init(vq);
 }