From 4623e5967448444a4ea1e77beb58898c4af48693 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Thu, 29 Oct 2015 03:02:06 -0200 Subject: [PATCH] [media] vb2: fix a regression in poll() behavior for output,streams 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 Acked-by: Laurent Pinchart Cc: # for v3.17 and up Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- drivers/media/v4l2-core/videobuf2-v4l2.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c index 27b4b9e..502984c 100644 --- a/drivers/media/v4l2-core/videobuf2-v4l2.c +++ b/drivers/media/v4l2-core/videobuf2-v4l2.c @@ -822,10 +822,10 @@ 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 (q->is_output && q->queued_count < q->num_buffers) + if (q->is_output && q->fileio && q->queued_count < q->num_buffers) return res | POLLOUT | POLLWRNORM; if (list_empty(&q->done_list)) { -- 2.7.4