059b1c5b15
SPDX v3.10 gained support for GFDL-1.1 with no invariant sections: https://spdx.org/licenses/GFDL-1.1-no-invariants-or-later.html So, remove the license text, replacing them by this new SPDX license. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
59 lines
1.3 KiB
ReStructuredText
59 lines
1.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
|
|
|
|
.. _VIDIOC_PREPARE_BUF:
|
|
|
|
************************
|
|
ioctl VIDIOC_PREPARE_BUF
|
|
************************
|
|
|
|
Name
|
|
====
|
|
|
|
VIDIOC_PREPARE_BUF - Prepare a buffer for I/O
|
|
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:function:: int ioctl( int fd, VIDIOC_PREPARE_BUF, struct v4l2_buffer *argp )
|
|
:name: VIDIOC_PREPARE_BUF
|
|
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :ref:`open() <func-open>`.
|
|
|
|
``argp``
|
|
Pointer to struct :c:type:`v4l2_buffer`.
|
|
|
|
|
|
Description
|
|
===========
|
|
|
|
Applications can optionally call the :ref:`VIDIOC_PREPARE_BUF` ioctl to
|
|
pass ownership of the buffer to the driver before actually enqueuing it,
|
|
using the :ref:`VIDIOC_QBUF <VIDIOC_QBUF>` ioctl, and to prepare it for future I/O. Such
|
|
preparations may include cache invalidation or cleaning. Performing them
|
|
in advance saves time during the actual I/O.
|
|
|
|
The struct :c:type:`v4l2_buffer` structure is specified in
|
|
:ref:`buffer`.
|
|
|
|
|
|
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.
|
|
|
|
EBUSY
|
|
File I/O is in progress.
|
|
|
|
EINVAL
|
|
The buffer ``type`` is not supported, or the ``index`` is out of
|
|
bounds, or no buffers have been allocated yet, or the ``userptr`` or
|
|
``length`` are invalid.
|