@@ -2622,10 +2622,10 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
return res | POLLERR;
/*
- * For output streams you can write as long as there are fewer buffers
- * queued than there are buffers available.
+ * For output streams you can call write() as long as there are fewer
+ * buffers queued than there are buffers available.
*/
- if (V4L2_TYPE_IS_OUTPUT(q->type) && q->queued_count < q->num_buffers)
+ if (V4L2_TYPE_IS_OUTPUT(q->type) && q->fileio && q->queued_count < q->num_buffers)
return res | POLLOUT | POLLWRNORM;
if (list_empty(&q->done_list))
This is a note to let you know that I have just added a patch titled [media] vb2: fix a regression in poll() behavior for output,streams to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt14. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 26b557e4f168aed99e11b833783388340ff4eb0f Mon Sep 17 00:00:00 2001 From: Hans Verkuil <hverkuil@xs4all.nl> Date: Thu, 29 Oct 2015 03:02:06 -0200 Subject: [media] vb2: fix a regression in poll() behavior for output,streams commit 4623e5967448444a4ea1e77beb58898c4af48693 upstream. In the 3.17 kernel the poll() behavior changed for output streams: as long as not all buffers were queued up poll() would return that userspace can write. This is fine for the write() call, but when using stream I/O this changed the behavior since the expectation was that it would wait for buffers to become available for dequeuing. This patch only enables the check whether you can queue buffers for file I/O only, and skips it for stream I/O. Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> [ kamal: backport to 4.2-stable: file rename; context ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/media/v4l2-core/videobuf2-core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- 1.9.1