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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>
97 lines
4.1 KiB
ReStructuredText
97 lines
4.1 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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.. _rf-tuner-controls:
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**************************
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RF Tuner Control Reference
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**************************
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The RF Tuner (RF_TUNER) class includes controls for common features of
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devices having RF tuner.
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In this context, RF tuner is radio receiver circuit between antenna and
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demodulator. It receives radio frequency (RF) from the antenna and
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converts that received signal to lower intermediate frequency (IF) or
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baseband frequency (BB). Tuners that could do baseband output are often
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called Zero-IF tuners. Older tuners were typically simple PLL tuners
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inside a metal box, while newer ones are highly integrated chips
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without a metal box "silicon tuners". These controls are mostly
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applicable for new feature rich silicon tuners, just because older
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tuners does not have much adjustable features.
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For more information about RF tuners see
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`Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
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and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
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from Wikipedia.
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.. _rf-tuner-control-id:
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RF_TUNER Control IDs
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====================
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``V4L2_CID_RF_TUNER_CLASS (class)``
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The RF_TUNER class descriptor. Calling
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:ref:`VIDIOC_QUERYCTRL` for this control will
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return a description of this control class.
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``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
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Enables/disables tuner radio channel bandwidth configuration. In
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automatic mode bandwidth configuration is performed by the driver.
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``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
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Filter(s) on tuner signal path are used to filter signal according
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to receiving party needs. Driver configures filters to fulfill
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desired bandwidth requirement. Used when
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V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
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range and step are driver-specific.
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``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
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Enables/disables LNA automatic gain control (AGC)
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``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
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Enables/disables mixer automatic gain control (AGC)
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``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
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Enables/disables IF automatic gain control (AGC)
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``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
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The RF amplifier is the very first amplifier on the receiver signal
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path, just right after the antenna input. The difference between the
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LNA gain and the RF gain in this document is that the LNA gain is
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integrated in the tuner chip while the RF gain is a separate chip.
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There may be both RF and LNA gain controls in the same device. The
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range and step are driver-specific.
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``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
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LNA (low noise amplifier) gain is first gain stage on the RF tuner
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signal path. It is located very close to tuner antenna input. Used
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when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
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``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
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differs from the each others. The range and step are
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driver-specific.
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``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
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Mixer gain is second gain stage on the RF tuner signal path. It is
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located inside mixer block, where RF signal is down-converted by the
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mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
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The range and step are driver-specific.
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``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
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IF gain is last gain stage on the RF tuner signal path. It is
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located on output of RF tuner. It controls signal level of
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intermediate frequency output or baseband output. Used when
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``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
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are driver-specific.
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``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
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Is synthesizer PLL locked? RF tuner is receiving given frequency
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when that control is set. This is a read-only control.
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