[media] vb2: fix VBI/poll regression

The recent conversion of saa7134 to vb2 unconvered a poll() bug that broke the teletext applications alevt and mtt. These applications expect that calling poll() without having called VIDIOC_STREAMON will cause poll() to return POLLERR. That did not happen in vb2. This patch fixes that behavior. It also fixes what should happen when poll() is called when STREAMON is called but no buffers have been queued. In that case poll() will also return POLLERR, but only for capture queues since output queues will always return POLLOUT anyway in that situation. This brings the vb2 behavior in line with the old videobuf behavior. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

[media] vb2: fix VBI/poll regression
The recent conversion of saa7134 to vb2 unconvered a poll() bug that broke the teletext applications alevt and mtt. These applications expect that calling poll() without having called VIDIOC_STREAMON will cause poll() to return POLLERR. That did not happen in vb2. This patch fixes that behavior. It also fixes what should happen when poll() is called when STREAMON is called but no buffers have been queued. In that case poll() will also return POLLERR, but only for capture queues since output queues will always return POLLOUT anyway in that situation. This brings the vb2 behavior in line with the old videobuf behavior. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Hans Verkuil · Mauro Carvalho Chehab · Eric Lee · Eric Lee · Eric Lee · Eric Lee
1 parent 50394e7369
Showing 2 changed files with 18 additions and 3 deletions Side-by-side Diff
drivers/media/v4l2-core/videobuf2-core.c
include/media/videobuf2-core.h
@@ -971,6 +971,7 @@
 	 * to the userspace.
 	 */
 	req->count = allocated_buffers;
+	q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
  
 	return 0;
 }
@@ -1018,6 +1019,7 @@
 		memset(q->plane_sizes, 0, sizeof(q->plane_sizes));
 		memset(q->alloc_ctx, 0, sizeof(q->alloc_ctx));
 		q->memory = create->memory;
+		q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
 	}
  
 	num_buffers = min(create->count, VIDEO_MAX_FRAME - q->num_buffers);
@@ -1821,6 +1823,7 @@
 	 */
 	list_add_tail(&vb->queued_entry, &q->queued_list);
 	q->queued_count++;
+	q->waiting_for_buffers = false;
 	vb->state = VB2_BUF_STATE_QUEUED;
 	if (V4L2_TYPE_IS_OUTPUT(q->type)) {
 		/*
@@ -2287,6 +2290,7 @@
 	 * their normal dequeued state.
 	 */
 	__vb2_queue_cancel(q);
+	q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
  
 	dprintk(3, "successful\n");
 	return 0;
  
@@ -2605,10 +2609,17 @@
 	}
  
 	/*
-	 * There is nothing to wait for if no buffer has been queued and the
-	 * queue isn't streaming, or if the error flag is set.
+	 * There is nothing to wait for if the queue isn't streaming, or if the
+	 * error flag is set.
 	 */
-	if ((list_empty(&q->queued_list) && !vb2_is_streaming(q)) || q->error)
+	if (!vb2_is_streaming(q) || q->error)
+		return res | POLLERR;
+	/*
+	 * For compatibility with vb1: if QBUF hasn't been called yet, then
+	 * return POLLERR as well. This only affects capture queues, output
+	 * queues will always initialize waiting_for_buffers to false.
+	 */
+	if (q->waiting_for_buffers)
 		return res | POLLERR;
  
 	/*
@@ -380,6 +380,9 @@
  * @start_streaming_called: start_streaming() was called successfully and we
  *		started streaming.
  * @error:	a fatal error occurred on the queue
+ * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for
+ *		buffers. Only set for capture queues if qbuf has not yet been
+ *		called since poll() needs to return POLLERR in that situation.
  * @fileio:	file io emulator internal data, used only if emulator is active
  * @threadio:	thread io internal data, used only if thread is active
  */
@@ -417,6 +420,7 @@
 	unsigned int			streaming:1;
 	unsigned int			start_streaming_called:1;
 	unsigned int			error:1;
+	unsigned int			waiting_for_buffers:1;
  
 	struct vb2_fileio_data		*fileio;
 	struct vb2_threadio_data	*threadio;
...	...	@@ -971,6 +971,7 @@
971	971	* to the userspace.
972	972	*/
973	973	req->count = allocated_buffers;
	974	+ q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
974	975
975	976	return 0;
976	977	}
...	...	@@ -1018,6 +1019,7 @@
1018	1019	memset(q->plane_sizes, 0, sizeof(q->plane_sizes));
1019	1020	memset(q->alloc_ctx, 0, sizeof(q->alloc_ctx));
1020	1021	q->memory = create->memory;
	1022	+ q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
1021	1023	}
1022	1024
1023	1025	num_buffers = min(create->count, VIDEO_MAX_FRAME - q->num_buffers);
...	...	@@ -1821,6 +1823,7 @@
1821	1823	*/
1822	1824	list_add_tail(&vb->queued_entry, &q->queued_list);
1823	1825	q->queued_count++;
	1826	+ q->waiting_for_buffers = false;
1824	1827	vb->state = VB2_BUF_STATE_QUEUED;
1825	1828	if (V4L2_TYPE_IS_OUTPUT(q->type)) {
1826	1829	/*
...	...	@@ -2287,6 +2290,7 @@
2287	2290	* their normal dequeued state.
2288	2291	*/
2289	2292	__vb2_queue_cancel(q);
	2293	+ q->waiting_for_buffers = !V4L2_TYPE_IS_OUTPUT(q->type);
2290	2294
2291	2295	dprintk(3, "successful\n");
2292	2296	return 0;
2293	2297
...	...	@@ -2605,10 +2609,17 @@
2605	2609	}
2606	2610
2607	2611	/*
2608		- * There is nothing to wait for if no buffer has been queued and the
2609		- * queue isn't streaming, or if the error flag is set.
	2612	+ * There is nothing to wait for if the queue isn't streaming, or if the
	2613	+ * error flag is set.
2610	2614	*/
2611		- if ((list_empty(&q->queued_list) && !vb2_is_streaming(q)) \|\| q->error)
	2615	+ if (!vb2_is_streaming(q) \|\| q->error)
	2616	+ return res \| POLLERR;
	2617	+ /*
	2618	+ * For compatibility with vb1: if QBUF hasn't been called yet, then
	2619	+ * return POLLERR as well. This only affects capture queues, output
	2620	+ * queues will always initialize waiting_for_buffers to false.
	2621	+ */
	2622	+ if (q->waiting_for_buffers)
2612	2623	return res \| POLLERR;
2613	2624
2614	2625	/*
...	...	@@ -380,6 +380,9 @@
380	380	* @start_streaming_called: start_streaming() was called successfully and we
381	381	* started streaming.
382	382	* @error: a fatal error occurred on the queue
	383	+ * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for
	384	+ * buffers. Only set for capture queues if qbuf has not yet been
	385	+ * called since poll() needs to return POLLERR in that situation.
383	386	* @fileio: file io emulator internal data, used only if emulator is active
384	387	* @threadio: thread io internal data, used only if thread is active
385	388	*/
...	...	@@ -417,6 +420,7 @@
417	420	unsigned int streaming:1;
418	421	unsigned int start_streaming_called:1;
419	422	unsigned int error:1;
	423	+ unsigned int waiting_for_buffers:1;
420	424
421	425	struct vb2_fileio_data *fileio;
422	426	struct vb2_threadio_data *threadio;