1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2 3.. _media-func-ioctl: 4 5************* 6media ioctl() 7************* 8 9Name 10==== 11 12media-ioctl - Control a media device 13 14 15Synopsis 16======== 17 18.. code-block:: c 19 20 #include <sys/ioctl.h> 21 22 23.. c:function:: int ioctl( int fd, int request, void *argp ) 24 :name: mc-ioctl 25 26Arguments 27========= 28 29``fd`` 30 File descriptor returned by :c:func:`open() <mc-open>`. 31 32``request`` 33 Media ioctl request code as defined in the media.h header file, for 34 example MEDIA_IOC_SETUP_LINK. 35 36``argp`` 37 Pointer to a request-specific structure. 38 39 40Description 41=========== 42 43The :ref:`ioctl() <media-func-ioctl>` function manipulates media device 44parameters. The argument ``fd`` must be an open file descriptor. 45 46The ioctl ``request`` code specifies the media function to be called. It 47has encoded in it whether the argument is an input, output or read/write 48parameter, and the size of the argument ``argp`` in bytes. 49 50Macros and structures definitions specifying media ioctl requests and 51their parameters are located in the media.h header file. All media ioctl 52requests, their respective function and parameters are specified in 53:ref:`media-user-func`. 54 55 56Return Value 57============ 58 59On success 0 is returned, on error -1 and the ``errno`` variable is set 60appropriately. The generic error codes are described at the 61:ref:`Generic Error Codes <gen-errors>` chapter. 62 63Request-specific error codes are listed in the individual requests 64descriptions. 65 66When an ioctl that takes an output or read/write parameter fails, the 67parameter remains unmodified. 68