[media] return BUF_STATE_ERROR if streaming stopped during acquisition

When stop_streaming is called while a frame is currently being retrieved, the
buffer being filled will still be returned with BUF_STATE_DONE. By resetting
the sequence number and checking before returning the buffer, it can now
correctly be returned with BUF_STATE_ERROR.

Signed-off-by: Martin Kaltenbrunner <[e-mail]>
Signed-off-by: Florian Echtler <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/input/touchscreen/sur40.c

···
 
 	dev_dbg(sur40->dev, "image acquired\n");
 
+	/* return error if streaming was stopped in the meantime */
+	if (sur40->sequence == -1)
+		goto err_poll;
+
 	/* mark as finished */
 	v4l2_get_timestamp(&new_buf->vb.v4l2_buf.timestamp);
 	new_buf->vb.v4l2_buf.sequence = sur40->sequence++;
···
 static void sur40_stop_streaming(struct vb2_queue *vq)
 {
 	struct sur40_state *sur40 = vb2_get_drv_priv(vq);
+	sur40->sequence = -1;
 
 	/* Release all active buffers */
 	return_all_buffers(sur40, VB2_BUF_STATE_ERROR);