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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/userspace-api/media/mediactl/media-ioc-request-alloc.rst | |
parent | Initial commit. (diff) | |
download | linux-430c2fc249ea5c0536abd21c23382884005c9093.tar.xz linux-430c2fc249ea5c0536abd21c23382884005c9093.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/userspace-api/media/mediactl/media-ioc-request-alloc.rst')
-rw-r--r-- | Documentation/userspace-api/media/mediactl/media-ioc-request-alloc.rst | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/mediactl/media-ioc-request-alloc.rst b/Documentation/userspace-api/media/mediactl/media-ioc-request-alloc.rst new file mode 100644 index 000000000..9195b4b8b --- /dev/null +++ b/Documentation/userspace-api/media/mediactl/media-ioc-request-alloc.rst @@ -0,0 +1,65 @@ +.. 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. |