| 1 | .. -*- coding: utf-8; mode: rst -*- |
| 2 | |
| 3 | .. _media-func-ioctl: |
| 4 | |
| 5 | ************* |
| 6 | media ioctl() |
| 7 | ************* |
| 8 | |
| 9 | Name |
| 10 | ==== |
| 11 | |
| 12 | media-ioctl - Control a media device |
| 13 | |
| 14 | |
| 15 | Synopsis |
| 16 | ======== |
| 17 | |
| 18 | .. code-block:: c |
| 19 | |
| 20 | #include <sys/ioctl.h> |
| 21 | |
| 22 | |
| 23 | .. cpp:function:: int ioctl( int fd, int request, void *argp ) |
| 24 | |
| 25 | |
| 26 | Arguments |
| 27 | ========= |
| 28 | |
| 29 | ``fd`` |
| 30 | File descriptor returned by :ref:`open() <func-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 | |
| 40 | Description |
| 41 | =========== |
| 42 | |
| 43 | The :ref:`ioctl() <media-func-ioctl>` function manipulates media device |
| 44 | parameters. The argument ``fd`` must be an open file descriptor. |
| 45 | |
| 46 | The ioctl ``request`` code specifies the media function to be called. It |
| 47 | has encoded in it whether the argument is an input, output or read/write |
| 48 | parameter, and the size of the argument ``argp`` in bytes. |
| 49 | |
| 50 | Macros and structures definitions specifying media ioctl requests and |
| 51 | their parameters are located in the media.h header file. All media ioctl |
| 52 | requests, their respective function and parameters are specified in |
| 53 | :ref:`media-user-func`. |
| 54 | |
| 55 | |
| 56 | Return Value |
| 57 | ============ |
| 58 | |
| 59 | On success 0 is returned, on error -1 and the ``errno`` variable is set |
| 60 | appropriately. The generic error codes are described at the |
| 61 | :ref:`Generic Error Codes <gen-errors>` chapter. |
| 62 | |
| 63 | Request-specific error codes are listed in the individual requests |
| 64 | descriptions. |
| 65 | |
| 66 | When an ioctl that takes an output or read/write parameter fails, the |
| 67 | parameter remains unmodified. |