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linux-next/Documentation/media/uapi/v4l/vidioc-enumaudio.rst
Mauro Carvalho Chehab 1473c75e9a media: v4l uAPI: add descriptions for arguments to all ioctls
Several ioctls are missing descriptions for the third argument
of the ioctl() command. They should have a description, as
otherwise the output won't be ok, and will sound like something
is missing.

So, add them.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-09-05 06:24:28 -04:00

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.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_ENUMAUDIO:
**********************
ioctl VIDIOC_ENUMAUDIO
**********************
Name
====
VIDIOC_ENUMAUDIO - Enumerate audio inputs
Synopsis
========
.. c:function:: int ioctl( int fd, VIDIOC_ENUMAUDIO, struct v4l2_audio *argp )
:name: VIDIOC_ENUMAUDIO
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``argp``
Pointer to struct :c:type:`v4l2_audio`.
Description
===========
To query the attributes of an audio input applications initialize the
``index`` field and zero out the ``reserved`` array of a struct
:c:type:`v4l2_audio` and call the :ref:`VIDIOC_ENUMAUDIO`
ioctl with a pointer to this structure. Drivers fill the rest of the
structure or return an ``EINVAL`` error code when the index is out of
bounds. To enumerate all audio inputs applications shall begin at index
zero, incrementing by one until the driver returns ``EINVAL``.
See :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` for a description of struct
:c:type:`v4l2_audio`.
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 audio input is out of bounds.