Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
57 lines
1.3 KiB
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57 lines
1.3 KiB
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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: V4L
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.. _VIDIOC_PREPARE_BUF:
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************************
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ioctl VIDIOC_PREPARE_BUF
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************************
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Name
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====
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VIDIOC_PREPARE_BUF - Prepare a buffer for I/O
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Synopsis
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========
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.. c:macro:: VIDIOC_PREPARE_BUF
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``int ioctl(int fd, VIDIOC_PREPARE_BUF, struct v4l2_buffer *argp)``
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Arguments
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=========
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``fd``
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File descriptor returned by :c:func:`open()`.
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``argp``
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Pointer to struct :c:type:`v4l2_buffer`.
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Description
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===========
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Applications can optionally call the :ref:`VIDIOC_PREPARE_BUF` ioctl to
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pass ownership of the buffer to the driver before actually enqueuing it,
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using the :ref:`VIDIOC_QBUF <VIDIOC_QBUF>` ioctl, and to prepare it for future I/O. Such
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preparations may include cache invalidation or cleaning. Performing them
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in advance saves time during the actual I/O.
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The struct :c:type:`v4l2_buffer` structure is specified in
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:ref:`buffer`.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EBUSY
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File I/O is in progress.
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EINVAL
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The buffer ``type`` is not supported, or the ``index`` is out of
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bounds, or no buffers have been allocated yet, or the ``userptr`` or
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``length`` are invalid.
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