| .. This file is dual-licensed: you can use it either under the terms |
| .. of the GPL 2.0 or the GFDL 1.1+ license, at your option. Note that this |
| .. dual licensing only applies to this file, and not this project as a |
| .. whole. |
| .. |
| .. a) This file is free software; you can redistribute it and/or |
| .. modify it under the terms of the GNU General Public License as |
| .. published by the Free Software Foundation version 2 of |
| .. the License. |
| .. |
| .. This file is distributed in the hope that it will be useful, |
| .. but WITHOUT ANY WARRANTY; without even the implied warranty of |
| .. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| .. GNU General Public License for more details. |
| .. |
| .. Or, alternatively, |
| .. |
| .. b) 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/media/uapi/fdl-appendix.rst. |
| .. |
| .. TODO: replace it to GPL-2.0 OR GFDL-1.1-or-later WITH no-invariant-sections |
| |
| .. _request-func-ioctl: |
| |
| *************** |
| request ioctl() |
| *************** |
| |
| Name |
| ==== |
| |
| request-ioctl - Control a request file descriptor |
| |
| |
| Synopsis |
| ======== |
| |
| .. code-block:: c |
| |
| #include <sys/ioctl.h> |
| |
| |
| .. c:function:: int ioctl( int fd, int cmd, void *argp ) |
| :name: req-ioctl |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :ref:`MEDIA_IOC_REQUEST_ALLOC`. |
| |
| ``cmd`` |
| The request ioctl command code as defined in the media.h header file, for |
| example :ref:`MEDIA_REQUEST_IOC_QUEUE`. |
| |
| ``argp`` |
| Pointer to a request-specific structure. |
| |
| |
| Description |
| =========== |
| |
| The :ref:`ioctl() <request-func-ioctl>` function manipulates request |
| parameters. The argument ``fd`` must be an open file descriptor. |
| |
| The ioctl ``cmd`` code specifies the request 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 request ioctl commands and |
| their parameters are located in the media.h header file. All request ioctl |
| commands, 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 <gen-errors>` chapter. |
| |
| Command-specific error codes are listed in the individual command |
| descriptions. |
| |
| When an ioctl that takes an output or read/write parameter fails, the |
| parameter remains unmodified. |