.. Permission is granted to copy, distribute and/or modify this .. document under the terms of the GNU Free Documentation License, .. Version 1.1 or any later version published by the Free Software .. Foundation, with no Invariant Sections, no Front-Cover Texts .. and no Back-Cover Texts. A copy of the license is included at .. Documentation/userspace-api/media/fdl-appendix.rst. .. .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _media-func-ioctl: ************* media ioctl() ************* Name ==== media-ioctl - Control a media device Synopsis ======== .. code-block:: c #include .. c:function:: int ioctl( int fd, int request, void *argp ) :name: mc-ioctl Arguments ========= ``fd`` File descriptor returned by :c:func:`open() `. ``request`` Media ioctl request code as defined in the media.h header file, for example MEDIA_IOC_SETUP_LINK. ``argp`` Pointer to a request-specific structure. Description =========== The :ref:`ioctl() ` function manipulates media device parameters. The argument ``fd`` must be an open file descriptor. The ioctl ``request`` code specifies the media 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 media ioctl requests and their parameters are located in the media.h header file. All media ioctl requests, their respective function and parameters are specified in :ref:`media-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 ` 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.