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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: MC3 4.. _media-func-ioctl:5 6*************7media ioctl()8*************9 10Name11====12 13media-ioctl - Control a media device14 15Synopsis16========17 18.. code-block:: c19 20 #include <sys/ioctl.h>21 22``int ioctl(int fd, int request, void *argp)``23 24Arguments25=========26 27``fd``28 File descriptor returned by :c:func:`open()`.29 30``request``31 Media ioctl request code as defined in the media.h header file, for32 example MEDIA_IOC_SETUP_LINK.33 34``argp``35 Pointer to a request-specific structure.36 37Description38===========39 40The :ref:`ioctl() <media-func-ioctl>` function manipulates media device41parameters. The argument ``fd`` must be an open file descriptor.42 43The ioctl ``request`` code specifies the media function to be called. It44has encoded in it whether the argument is an input, output or read/write45parameter, and the size of the argument ``argp`` in bytes.46 47Macros and structures definitions specifying media ioctl requests and48their parameters are located in the media.h header file. All media ioctl49requests, their respective function and parameters are specified in50:ref:`media-user-func`.51 52Return Value53============54 55On success 0 is returned, on error -1 and the ``errno`` variable is set56appropriately. The generic error codes are described at the57:ref:`Generic Error Codes <gen-errors>` chapter.58 59Request-specific error codes are listed in the individual requests60descriptions.61 62When an ioctl that takes an output or read/write parameter fails, the63parameter remains unmodified.64