[PATCH 0/1][SRU][OEM-5.10/H/U] Fix CS8409 crack sound on Bullseye

[You-Sheng Yang]

BugLink: https://bugs.launchpad.net/bugs/1924997

[Impact]

On a few CS8409 installed platforms, there are crack sounds when playing
audio with output volume set to 100%.

[Fix]

The hardware is not capable of generating smooth audio output at the
maximum volume that codec chip can be configured. A fix proposed to lower
the maximum output volume using CS8409 equalizer.

[Test Case]

Use GNOME Settings / Sound Settings, set volume to 100%, play test
audio for both right and left channels; set volume back to 70%, and
repeat the same to compare to differences. While we don't have acoustic
lab to perform precise measurements, the result was confirmed by
partner.

[Where problems could occur]

This is to add a preconfigured, equalizer driver default values. This
will introduce non-uniformed frequency response in comparison to that in
the hardware preset. The net effect observable to general users is a
lower maximum output volume. For those Hi-Fi users, audio output always
takes additional calibration via extra software like ALSAEqual and/or
hardware.

[Other Info]

By SRU we skipped a couple of refactoring changes in asound upstream
tree, so additional changes to the original patch are required to
backport.

Stefan Binding (1):
  UBUNTU: SAUCE: ALSA: hda/cirrus: Use CS8409 Equalizer to fix abnormal
    sounds on Bullseye

 sound/pci/hda/patch_cirrus.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

-- 
2.30.2