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diff --git a/Documentation/userspace-api/media/dvb/dmx-fwrite.rst b/Documentation/userspace-api/media/dvb/dmx-fwrite.rst new file mode 100644 index 000000000000..4400f4ef8c65 --- /dev/null +++ b/Documentation/userspace-api/media/dvb/dmx-fwrite.rst @@ -0,0 +1,79 @@ +.. Permission is granted to copy, distribute and/or modify this +.. document under the terms of the GNU Free Documentation License, +.. Version 1.1 or any later version published by the Free Software +.. Foundation, with no Invariant Sections, no Front-Cover Texts +.. and no Back-Cover Texts. A copy of the license is included at +.. Documentation/userspace-api/media/fdl-appendix.rst. +.. +.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections + +.. _dmx_fwrite: + +======================== +Digital TV demux write() +======================== + +Name +---- + +Digital TV demux write() + + +Synopsis +-------- + +.. c:function:: ssize_t write(int fd, const void *buf, size_t count) + :name: dvb-dmx-write + +Arguments +--------- + +``fd`` + File descriptor returned by a previous call to :c:func:`open() <dvb-ca-open>`. + +``buf`` + Buffer with data to be written + +``count`` + Number of bytes at the buffer + +Description +----------- + +This system call is only provided by the logical device +``/dev/dvb/adapter?/dvr?``, associated with the physical demux device that +provides the actual DVR functionality. It is used for replay of a +digitally recorded Transport Stream. Matching filters have to be defined +in the corresponding physical demux device, ``/dev/dvb/adapter?/demux?``. +The amount of data to be transferred is implied by count. + + +Return Value +------------ + +On success 0 is returned. + +On error -1 is returned, and the ``errno`` variable is set +appropriately. + +.. tabularcolumns:: |p{2.5cm}|p{15.0cm}| + +.. flat-table:: + :header-rows: 0 + :stub-columns: 0 + :widths: 1 16 + + - - ``EWOULDBLOCK`` + - No data was written. This might happen if ``O_NONBLOCK`` was + specified and there is no more buffer space available (if + ``O_NONBLOCK`` is not specified the function will block until buffer + space is available). + + - - ``EBUSY`` + - This error code indicates that there are conflicting requests. The + corresponding demux device is setup to receive data from the + front- end. Make sure that these filters are stopped and that the + filters with input set to ``DMX_IN_DVR`` are started. + +The generic error codes are described at the +:ref:`Generic Error Codes <gen-errors>` chapter. |