Documentation/admin-guide/media/si476x.rst

Source file repositories/reference/linux-study-clean/Documentation/admin-guide/media/si476x.rst

File Facts

System
Linux kernel
Corpus path
Documentation/admin-guide/media/si476x.rst
Extension
.rst
Size
6057 bytes
Lines
161
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

.. SPDX-License-Identifier: GPL-2.0

.. include:: <isonum.txt>


The SI476x Driver
=================

Copyright |copy| 2013 Andrey Smirnov <andrew.smirnov@gmail.com>

TODO for the driver
-------------------

- According to the SiLabs' datasheet it is possible to update the
  firmware of the radio chip in the run-time, thus bringing it to the
  most recent version. Unfortunately I couldn't find any mentioning of
  the said firmware update for the old chips that I tested the driver
  against, so for chips like that the driver only exposes the old
  functionality.


Parameters exposed over debugfs
-------------------------------
SI476x allow user to get multiple characteristics that can be very
useful for EoL testing/RF performance estimation, parameters that have
very little to do with V4L2 subsystem. Such parameters are exposed via
debugfs and can be accessed via regular file I/O operations.

The drivers exposes following files:

* /sys/kernel/debug/<device-name>/acf
  This file contains ACF(Automatically Controlled Features) status
  information. The contents of the file is binary data of the
  following layout:

  .. tabularcolumns:: |p{7ex}|p{12ex}|L|

  =============  ==============   ====================================
  Offset	 Name		  Description
  =============  ==============   ====================================
  0x00		 blend_int	  Flag, set when stereo separation has
				  crossed below the blend threshold
  0x01		 hblend_int	  Flag, set when HiBlend cutoff
				  frequency is lower than threshold
  0x02		 hicut_int	  Flag, set when HiCut cutoff
				  frequency is lower than threshold
  0x03		 chbw_int	  Flag, set when channel filter
				  bandwidth is less than threshold
  0x04		 softmute_int	  Flag indicating that softmute
				  attenuation has increased above
				  softmute threshold
  0x05		 smute		  0 - Audio is not soft muted
				  1 - Audio is soft muted
  0x06		 smattn		  Soft mute attenuation level in dB
  0x07		 chbw		  Channel filter bandwidth in kHz
  0x08		 hicut		  HiCut cutoff frequency in units of
				  100Hz
  0x09		 hiblend	  HiBlend cutoff frequency in units
				  of 100 Hz
  0x10		 pilot		  0 - Stereo pilot is not present
				  1 - Stereo pilot is present
  0x11		 stblend	  Stereo blend in %
  =============  ==============   ====================================


* /sys/kernel/debug/<device-name>/rds_blckcnt
  This file contains statistics about RDS receptions. It's binary data
  has the following layout:

  .. tabularcolumns:: |p{7ex}|p{12ex}|L|

Annotation

Implementation Notes