Based on kernel version 6.11
. Page generated on 2024-09-24 08:21 EST
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 | .. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later .. c:namespace:: MC .. _media_ioc_request_alloc: ***************************** ioctl MEDIA_IOC_REQUEST_ALLOC ***************************** Name ==== MEDIA_IOC_REQUEST_ALLOC - Allocate a request Synopsis ======== .. c:macro:: MEDIA_IOC_REQUEST_ALLOC ``int ioctl(int fd, MEDIA_IOC_REQUEST_ALLOC, int *argp)`` Arguments ========= ``fd`` File descriptor returned by :c:func:`open()`. ``argp`` Pointer to an integer. Description =========== If the media device supports :ref:`requests <media-request-api>`, then this ioctl can be used to allocate a request. If it is not supported, then ``errno`` is set to ``ENOTTY``. A request is accessed through a file descriptor that is returned in ``*argp``. If the request was successfully allocated, then the request file descriptor can be passed to the :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`, :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`, :ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and :ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` ioctls. In addition, the request can be queued by calling :ref:`MEDIA_REQUEST_IOC_QUEUE` and re-initialized by calling :ref:`MEDIA_REQUEST_IOC_REINIT`. Finally, the file descriptor can be :ref:`polled <request-func-poll>` to wait for the request to complete. The request will remain allocated until all the file descriptors associated with it are closed by :c:func:`close()` and the driver no longer uses the request internally. See also :ref:`here <media-request-life-time>` for more information. 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. ENOTTY The driver has no support for requests. |