linux-stable/Documentation/sound/hd-audio
Thomas Hebb f47413b98c ALSA: doc: Document PC Beep Hidden Register on Realtek ALC256
commit f128090491 upstream.

This codec (among others) has a hidden set of audio routes, apparently
designed to allow PC Beep output without a mixer widget on the output
path, which are controlled by an undocumented Realtek vendor register.
The default configuration of these routes means that certain inputs
aren't accessible, necessitating driver control of the register.
However, Realtek has provided no documentation of the register, instead
opting to fix issues by providing magic numbers, most of which have been
at least somewhat erroneous. These magic numbers then get copied by
others into model-specific fixups, leading to a fragmented and buggy set
of configurations.

To get out of this situation, I've reverse engineered the register by
flipping bits and observing how the codec's behavior changes. This
commit documents my findings. It does not change any code.

Cc: stable@vger.kernel.org
Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>
Link: https://lore.kernel.org/r/bd69dfdeaf40ff31c4b7b797c829bb320031739c.1585584498.git.tommyhebb@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-24 08:00:35 +02:00
..
controls.rst ALSA: doc: ReSTize HD-Audio-Controls document 2016-11-10 17:59:22 +01:00
dp-mst.rst ALSA: Documentation about HDA DP MST pin init and connection 2017-01-12 10:06:47 +01:00
index.rst ALSA: doc: Document PC Beep Hidden Register on Realtek ALC256 2020-04-24 08:00:35 +02:00
models.rst ALSA: hda - Update the list of quirk models 2017-05-22 16:42:02 +02:00
notes.rst ALSA: hda - Allow to enable/disable vmaster build explicitly 2017-04-10 17:45:27 +02:00
realtek-pc-beep.rst ALSA: doc: Document PC Beep Hidden Register on Realtek ALC256 2020-04-24 08:00:35 +02:00