1059b1c5bSMauro Carvalho Chehab.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 254f38fcaSMauro Carvalho Chehab 354f38fcaSMauro Carvalho Chehab.. _func-ioctl: 454f38fcaSMauro Carvalho Chehab 554f38fcaSMauro Carvalho Chehab************ 654f38fcaSMauro Carvalho ChehabV4L2 ioctl() 754f38fcaSMauro Carvalho Chehab************ 854f38fcaSMauro Carvalho Chehab 954f38fcaSMauro Carvalho ChehabName 1054f38fcaSMauro Carvalho Chehab==== 1154f38fcaSMauro Carvalho Chehab 1254f38fcaSMauro Carvalho Chehabv4l2-ioctl - Program a V4L2 device 1354f38fcaSMauro Carvalho Chehab 1454f38fcaSMauro Carvalho Chehab 1554f38fcaSMauro Carvalho ChehabSynopsis 1654f38fcaSMauro Carvalho Chehab======== 1754f38fcaSMauro Carvalho Chehab 1854f38fcaSMauro Carvalho Chehab.. code-block:: c 1954f38fcaSMauro Carvalho Chehab 2054f38fcaSMauro Carvalho Chehab #include <sys/ioctl.h> 2154f38fcaSMauro Carvalho Chehab 2254f38fcaSMauro Carvalho Chehab 2354f38fcaSMauro Carvalho Chehab.. c:function:: int ioctl( int fd, int request, void *argp ) 2454f38fcaSMauro Carvalho Chehab :name: v4l2-ioctl 2554f38fcaSMauro Carvalho Chehab 2654f38fcaSMauro Carvalho ChehabArguments 2754f38fcaSMauro Carvalho Chehab========= 2854f38fcaSMauro Carvalho Chehab 2954f38fcaSMauro Carvalho Chehab``fd`` 3054f38fcaSMauro Carvalho Chehab File descriptor returned by :ref:`open() <func-open>`. 3154f38fcaSMauro Carvalho Chehab 3254f38fcaSMauro Carvalho Chehab``request`` 3354f38fcaSMauro Carvalho Chehab V4L2 ioctl request code as defined in the ``videodev2.h`` header 3454f38fcaSMauro Carvalho Chehab file, for example VIDIOC_QUERYCAP. 3554f38fcaSMauro Carvalho Chehab 3654f38fcaSMauro Carvalho Chehab``argp`` 3754f38fcaSMauro Carvalho Chehab Pointer to a function parameter, usually a structure. 3854f38fcaSMauro Carvalho Chehab 3954f38fcaSMauro Carvalho Chehab 4054f38fcaSMauro Carvalho ChehabDescription 4154f38fcaSMauro Carvalho Chehab=========== 4254f38fcaSMauro Carvalho Chehab 4354f38fcaSMauro Carvalho ChehabThe :ref:`ioctl() <func-ioctl>` function is used to program V4L2 devices. The 4454f38fcaSMauro Carvalho Chehabargument ``fd`` must be an open file descriptor. An ioctl ``request`` 4554f38fcaSMauro Carvalho Chehabhas encoded in it whether the argument is an input, output or read/write 4654f38fcaSMauro Carvalho Chehabparameter, and the size of the argument ``argp`` in bytes. Macros and 4754f38fcaSMauro Carvalho Chehabdefines specifying V4L2 ioctl requests are located in the 4854f38fcaSMauro Carvalho Chehab``videodev2.h`` header file. Applications should use their own copy, not 4954f38fcaSMauro Carvalho Chehabinclude the version in the kernel sources on the system they compile on. 5054f38fcaSMauro Carvalho ChehabAll V4L2 ioctl requests, their respective function and parameters are 5154f38fcaSMauro Carvalho Chehabspecified in :ref:`user-func`. 5254f38fcaSMauro Carvalho Chehab 5354f38fcaSMauro Carvalho Chehab 5454f38fcaSMauro Carvalho ChehabReturn Value 5554f38fcaSMauro Carvalho Chehab============ 5654f38fcaSMauro Carvalho Chehab 5754f38fcaSMauro Carvalho ChehabOn success 0 is returned, on error -1 and the ``errno`` variable is set 5854f38fcaSMauro Carvalho Chehabappropriately. The generic error codes are described at the 5954f38fcaSMauro Carvalho Chehab:ref:`Generic Error Codes <gen-errors>` chapter. 6054f38fcaSMauro Carvalho Chehab 6154f38fcaSMauro Carvalho ChehabWhen an ioctl that takes an output or read/write parameter fails, the 6254f38fcaSMauro Carvalho Chehabparameter remains unmodified. 63