linux_dsm_epyc7002/Documentation/linux_tv/media/v4l/vidioc-g-output.rst
Mauro Carvalho Chehab b7e67f6c1b doc-rst: linux_tv: supress lots of warnings
The c language parser checks if there are duplicated object
definitions. That causes lots of warnings like:
	WARNING: duplicate C object description of ioctl

Let's remove those by telling Sphinx that the language for
those objects are c++. The look of the descriptions will
be close, and the warnings will be gone.

Please notice that we had to keep a few of them as C, as
the c++ parser seems to be broken when it finds an enum.

Yet, this reduced from 219 warnings to 143, with is
a good thing.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-07-03 10:05:16 -03:00

73 lines
2.1 KiB
ReStructuredText

.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_G_OUTPUT:
**************************************
ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
**************************************
*man VIDIOC_G_OUTPUT(2)*
VIDIOC_S_OUTPUT
Query or select the current video output
Synopsis
========
.. cpp:function:: int ioctl( int fd, int request, int *argp )
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``request``
VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT
``argp``
Description
===========
To query the current video output applications call the
:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a pointer to an integer where the driver
stores the number of the output, as in the struct
:ref:`v4l2_output <v4l2-output>` ``index`` field. This ioctl will
fail only when there are no video outputs, returning the EINVAL error
code.
To select a video output applications store the number of the desired
output in an integer and call the :ref:`VIDIOC_S_OUTPUT <VIDIOC_G_OUTPUT>` ioctl with a
pointer to this integer. Side effects are possible. For example outputs
may support different video standards, so the driver may implicitly
switch the current standard. standard. Because of these possible side
effects applications must select an output before querying or
negotiating any other parameters.
Information about video outputs is available using the
:ref:`VIDIOC_ENUMOUTPUT` ioctl.
Return Value
============
On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.
EINVAL
The number of the video output is out of bounds, or there are no
video outputs at all.
.. ------------------------------------------------------------------------------
.. This file was automatically converted from DocBook-XML with the dbxml
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
.. from the linux kernel, refer to:
..
.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
.. ------------------------------------------------------------------------------