Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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
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+.. 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.