From acf92046a0a666051f9c6b4a53d874c618203173 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sat, 20 Sep 2014 16:16:36 -0300 Subject: [media] DocBook media: fix the poll() 'no QBUF' documentation Clarify what poll() returns if STREAMON was called but not QBUF. Make explicit the different behavior for this scenario for capture and output devices. Signed-off-by: Hans Verkuil Acked-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab --- Documentation/DocBook/media/v4l/func-poll.xml | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'Documentation/DocBook/media') diff --git a/Documentation/DocBook/media/v4l/func-poll.xml b/Documentation/DocBook/media/v4l/func-poll.xml index 85cad8bff5ba..bd07104a35e9 100644 --- a/Documentation/DocBook/media/v4l/func-poll.xml +++ b/Documentation/DocBook/media/v4l/func-poll.xml @@ -44,10 +44,18 @@ Capture devices set the POLLIN and flags. When the function timed out it returns a value of zero, on failure it returns -1 and the errno variable is set appropriately. When the -application did not call &VIDIOC-QBUF; or &VIDIOC-STREAMON; yet the +application did not call &VIDIOC-STREAMON; the poll() function succeeds, but sets the POLLERR flag in the -revents field. +revents field. When the +application has called &VIDIOC-STREAMON; for a capture device but hasn't +yet called &VIDIOC-QBUF;, the poll() function +succeeds and sets the POLLERR flag in the +revents field. For output devices this +same situation will cause poll() to succeed +as well, but it sets the POLLOUT and +POLLWRNORM flags in the revents +field. When use of the read() function has been negotiated and the driver does not capture yet, the -- cgit v1.2.3