linux/Documentation/media/uapi/cec/cec-func-ioctl.rst
Mauro Carvalho Chehab 9954783662 [media] docs-rst: Convert CEC uAPI to use C function references
Name all ioctl references and make them match the ioctls that
are documented. That will improve the cross-reference index,
as it will have all ioctls and syscalls there.

While here, improve the documentation to make them to look more
like the rest of the document.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-08-22 21:23:40 -03:00

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1.6 KiB
ReStructuredText

.. -*- coding: utf-8; mode: rst -*-
.. _cec-func-ioctl:
***********
cec ioctl()
***********
Name
====
cec-ioctl - Control a cec device
Synopsis
========
.. code-block:: c
#include <sys/ioctl.h>
.. c:function:: int ioctl( int fd, int request, void *argp )
:name: cec-ioctl
Arguments
=========
``fd``
File descriptor returned by :c:func:`open() <cec-open>`.
``request``
CEC ioctl request code as defined in the cec.h header file, for
example :c:func:`CEC_ADAP_G_CAPS`.
``argp``
Pointer to a request-specific structure.
Description
===========
.. note::
This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
The :c:func:`ioctl()` function manipulates cec device parameters. The
argument ``fd`` must be an open file descriptor.
The ioctl ``request`` code specifies the cec function to be called. It
has encoded in it whether the argument is an input, output or read/write
parameter, and the size of the argument ``argp`` in bytes.
Macros and structures definitions specifying cec ioctl requests and
their parameters are located in the cec.h header file. All cec ioctl
requests, their respective function and parameters are specified in
:ref:`cec-user-func`.
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.
Request-specific error codes are listed in the individual requests
descriptions.
When an ioctl that takes an output or read/write parameter fails, the
parameter remains unmodified.