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Fix typos and punctuation and improve grammar in documentation. Signed-off-by: Hanne-Lotta Mäenpää <hannelotta@gmail.com> Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
57 lines
1.4 KiB
ReStructuredText
57 lines
1.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: DTV.fe
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.. _FE_SET_TONE:
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*****************
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ioctl FE_SET_TONE
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*****************
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Name
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====
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FE_SET_TONE - Sets/resets the generation of the continuous 22kHz tone.
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Synopsis
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========
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.. c:macro:: FE_SET_TONE
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``int ioctl(int fd, FE_SET_TONE, enum fe_sec_tone_mode tone)``
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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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``tone``
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An integer enumerated value described at :c:type:`fe_sec_tone_mode`
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Description
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===========
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This ioctl is used to set the generation of the continuous 22kHz tone.
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This call requires read/write permissions.
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Usually, satellite antenna subsystems require that the digital TV device
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to send a 22kHz tone in order to select between high/low band on some
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dual-band LNBf. It is also used to send signals to DiSEqC equipment, but
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this is done using the DiSEqC ioctls.
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.. attention:: If more than one device is connected to the same antenna,
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setting a tone may interfere on other devices, as they may lose the
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capability of selecting the band. So, it is recommended that applications
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would change to SEC_TONE_OFF when the device is not used.
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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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Generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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