| .. -*- coding: utf-8; mode: rst -*- |
| |
| .. _func-ioctl: |
| |
| ************ |
| V4L2 ioctl() |
| ************ |
| |
| Name |
| ==== |
| |
| v4l2-ioctl - Program a V4L2 device |
| |
| |
| Synopsis |
| ======== |
| |
| .. code-block:: c |
| |
| #include <sys/ioctl.h> |
| |
| |
| .. c:function:: int ioctl( int fd, int request, void *argp ) |
| :name: v4l2-ioctl |
| |
| Arguments |
| ========= |
| |
| ``fd`` |
| File descriptor returned by :ref:`open() <func-open>`. |
| |
| ``request`` |
| V4L2 ioctl request code as defined in the ``videodev2.h`` header |
| file, for example VIDIOC_QUERYCAP. |
| |
| ``argp`` |
| Pointer to a function parameter, usually a structure. |
| |
| |
| Description |
| =========== |
| |
| The :ref:`ioctl() <func-ioctl>` function is used to program V4L2 devices. The |
| argument ``fd`` must be an open file descriptor. An ioctl ``request`` |
| 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 |
| defines specifying V4L2 ioctl requests are located in the |
| ``videodev2.h`` header file. Applications should use their own copy, not |
| include the version in the kernel sources on the system they compile on. |
| All V4L2 ioctl requests, their respective function and parameters are |
| specified in :ref:`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. |
| |
| When an ioctl that takes an output or read/write parameter fails, the |
| parameter remains unmodified. |
