1 .. SPDX-License-Identifier: GFDL-1.1-no-invari !! 1 .. Permission is granted to copy, distribute and/or modify this
2 .. c:namespace:: V4L !! 2 .. document under the terms of the GNU Free Documentation License,
>> 3 .. Version 1.1 or any later version published by the Free Software
>> 4 .. Foundation, with no Invariant Sections, no Front-Cover Texts
>> 5 .. and no Back-Cover Texts. A copy of the license is included at
>> 6 .. Documentation/userspace-api/media/fdl-appendix.rst.
>> 7 ..
>> 8 .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
3 9
4 .. _func-ioctl: 10 .. _func-ioctl:
5 11
6 ************ 12 ************
7 V4L2 ioctl() 13 V4L2 ioctl()
8 ************ 14 ************
9 15
10 Name 16 Name
11 ==== 17 ====
12 18
13 v4l2-ioctl - Program a V4L2 device 19 v4l2-ioctl - Program a V4L2 device
14 20
>> 21
15 Synopsis 22 Synopsis
16 ======== 23 ========
17 24
18 .. code-block:: c 25 .. code-block:: c
19 26
20 #include <sys/ioctl.h> 27 #include <sys/ioctl.h>
21 28
22 ``int ioctl(int fd, int request, void *argp)`` !! 29
>> 30 .. c:function:: int ioctl( int fd, int request, void *argp )
>> 31 :name: v4l2-ioctl
23 32
24 Arguments 33 Arguments
25 ========= 34 =========
26 35
27 ``fd`` 36 ``fd``
28 File descriptor returned by :c:func:`open( !! 37 File descriptor returned by :ref:`open() <func-open>`.
29 38
30 ``request`` 39 ``request``
31 V4L2 ioctl request code as defined in the 40 V4L2 ioctl request code as defined in the ``videodev2.h`` header
32 file, for example VIDIOC_QUERYCAP. 41 file, for example VIDIOC_QUERYCAP.
33 42
34 ``argp`` 43 ``argp``
35 Pointer to a function parameter, usually a 44 Pointer to a function parameter, usually a structure.
36 45
>> 46
37 Description 47 Description
38 =========== 48 ===========
39 49
40 The :ref:`ioctl() <func-ioctl>` function is us 50 The :ref:`ioctl() <func-ioctl>` function is used to program V4L2 devices. The
41 argument ``fd`` must be an open file descripto 51 argument ``fd`` must be an open file descriptor. An ioctl ``request``
42 has encoded in it whether the argument is an i 52 has encoded in it whether the argument is an input, output or read/write
43 parameter, and the size of the argument ``argp 53 parameter, and the size of the argument ``argp`` in bytes. Macros and
44 defines specifying V4L2 ioctl requests are loc 54 defines specifying V4L2 ioctl requests are located in the
45 ``videodev2.h`` header file. Applications shou 55 ``videodev2.h`` header file. Applications should use their own copy, not
46 include the version in the kernel sources on t 56 include the version in the kernel sources on the system they compile on.
47 All V4L2 ioctl requests, their respective func 57 All V4L2 ioctl requests, their respective function and parameters are
48 specified in :ref:`user-func`. 58 specified in :ref:`user-func`.
>> 59
49 60
50 Return Value 61 Return Value
51 ============ 62 ============
52 63
53 On success 0 is returned, on error -1 and the 64 On success 0 is returned, on error -1 and the ``errno`` variable is set
54 appropriately. The generic error codes are des 65 appropriately. The generic error codes are described at the
55 :ref:`Generic Error Codes <gen-errors>` chapte 66 :ref:`Generic Error Codes <gen-errors>` chapter.
56 67
57 When an ioctl that takes an output or read/wri 68 When an ioctl that takes an output or read/write parameter fails, the
58 parameter remains unmodified. 69 parameter remains unmodified.
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