54f38fcae5
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
80 lines
2.2 KiB
ReStructuredText
80 lines
2.2 KiB
ReStructuredText
.. Permission is granted to copy, distribute and/or modify this
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.. document under the terms of the GNU Free Documentation License,
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.. Version 1.1 or any later version published by the Free Software
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.. Foundation, with no Invariant Sections, no Front-Cover Texts
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.. and no Back-Cover Texts. A copy of the license is included at
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.. Documentation/userspace-api/media/fdl-appendix.rst.
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..
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.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
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.. _dmx_fwrite:
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========================
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Digital TV demux write()
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========================
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Name
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----
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Digital TV demux write()
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Synopsis
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--------
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.. c:function:: ssize_t write(int fd, const void *buf, size_t count)
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:name: dvb-dmx-write
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Arguments
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---------
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``fd``
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File descriptor returned by a previous call to :c:func:`open() <dvb-ca-open>`.
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``buf``
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Buffer with data to be written
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``count``
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Number of bytes at the buffer
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Description
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-----------
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This system call is only provided by the logical device
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``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that
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provides the actual DVR functionality. It is used for replay of a
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digitally recorded Transport Stream. Matching filters have to be defined
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in the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``.
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The amount of data to be transferred is implied by count.
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Return Value
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------------
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On success 0 is returned.
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On error -1 is returned, and the ``errno`` variable is set
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appropriately.
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.. tabularcolumns:: |p{2.5cm}|p{15.0cm}|
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.. flat-table::
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 16
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- - ``EWOULDBLOCK``
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- No data was written. This might happen if ``O_NONBLOCK`` was
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specified and there is no more buffer space available (if
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``O_NONBLOCK`` is not specified the function will block until buffer
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space is available).
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- - ``EBUSY``
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- This error code indicates that there are conflicting requests. The
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corresponding demux device is setup to receive data from the
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front- end. Make sure that these filters are stopped and that the
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filters with input set to ``DMX_IN_DVR`` are started.
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The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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