mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-19 02:04:19 +08:00
54f38fcae5
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
86 lines
2.2 KiB
ReStructuredText
86 lines
2.2 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
|
|
.. document under the terms of the GNU Free Documentation License,
|
|
.. Version 1.1 or any later version published by the Free Software
|
|
.. Foundation, with no Invariant Sections, no Front-Cover Texts
|
|
.. and no Back-Cover Texts. A copy of the license is included at
|
|
.. Documentation/userspace-api/media/fdl-appendix.rst.
|
|
..
|
|
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
|
|
|
|
.. _cec-func-poll:
|
|
|
|
**********
|
|
cec poll()
|
|
**********
|
|
|
|
Name
|
|
====
|
|
|
|
cec-poll - Wait for some event on a file descriptor
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. code-block:: c
|
|
|
|
#include <sys/poll.h>
|
|
|
|
|
|
.. c:function:: int poll( struct pollfd *ufds, unsigned int nfds, int timeout )
|
|
:name: cec-poll
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``ufds``
|
|
List of FD events to be watched
|
|
|
|
``nfds``
|
|
Number of FD events at the \*ufds array
|
|
|
|
``timeout``
|
|
Timeout to wait for events
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
With the :c:func:`poll() <cec-poll>` function applications can wait for CEC
|
|
events.
|
|
|
|
On success :c:func:`poll() <cec-poll>` returns the number of file descriptors
|
|
that have been selected (that is, file descriptors for which the
|
|
``revents`` field of the respective struct :c:type:`pollfd`
|
|
is non-zero). CEC devices set the ``POLLIN`` and ``POLLRDNORM`` flags in
|
|
the ``revents`` field if there are messages in the receive queue. If the
|
|
transmit queue has room for new messages, the ``POLLOUT`` and
|
|
``POLLWRNORM`` flags are set. If there are events in the event queue,
|
|
then the ``POLLPRI`` flag is set. When the function times out it returns
|
|
a value of zero, on failure it returns -1 and the ``errno`` variable is
|
|
set appropriately.
|
|
|
|
For more details see the :c:func:`poll() <cec-poll>` manual page.
|
|
|
|
|
|
Return Value
|
|
============
|
|
|
|
On success, :c:func:`poll() <cec-poll>` returns the number structures which have
|
|
non-zero ``revents`` fields, or zero if the call timed out. On error -1
|
|
is returned, and the ``errno`` variable is set appropriately:
|
|
|
|
``EBADF``
|
|
One or more of the ``ufds`` members specify an invalid file
|
|
descriptor.
|
|
|
|
``EFAULT``
|
|
``ufds`` references an inaccessible memory area.
|
|
|
|
``EINTR``
|
|
The call was interrupted by a signal.
|
|
|
|
``EINVAL``
|
|
The ``nfds`` value exceeds the ``RLIMIT_NOFILE`` value. Use
|
|
``getrlimit()`` to obtain this value.
|