| .. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later |
| .. c:namespace:: MC |
| |
| .. _request-func-ioctl: |
| |
| *************** |
| request ioctl() |
| *************** |
| |
| Name |
| ==== |
| |
| request-ioctl - Control a request file descriptor |
| |
| Synopsis |
| ======== |
| |
| .. code-block:: c |
| |
| #include <sys/ioctl.h> |
| |
| ``int ioctl(int fd, int cmd, void *argp)`` |
| |
| 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. |
