1 .. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later
4 .. _request-func-ioctl:
13 request-ioctl - Control a request file descriptor
20 #include <sys/ioctl.h>
22 ``int ioctl(int fd, int cmd, void *argp)``
28 File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`.
31 The request ioctl command code as defined in the media.h header file, for
32 example :ref:`MEDIA_REQUEST_IOC_QUEUE`.
35 Pointer to a request-specific structure.
40 The :ref:`ioctl() <request-func-ioctl>` function manipulates request
41 parameters. The argument ``fd`` must be an open file descriptor.
43 The ioctl ``cmd`` code specifies the request function to be called. It
44 has encoded in it whether the argument is an input, output or read/write
45 parameter, and the size of the argument ``argp`` in bytes.
47 Macros and structures definitions specifying request ioctl commands and
48 their parameters are located in the media.h header file. All request ioctl
49 commands, their respective function and parameters are specified in
50 :ref:`media-user-func`.
55 On success 0 is returned, on error -1 and the ``errno`` variable is set
56 appropriately. The generic error codes are described at the
57 :ref:`Generic Error Codes <gen-errors>` chapter.
59 Command-specific error codes are listed in the individual command
62 When an ioctl that takes an output or read/write parameter fails, the
63 parameter remains unmodified.