[SRU][N/M/J][PATCH 0/1] alsa/realtek: adjust max output valume for headphone on 2 LG machines

[Hui Wang]

BugLink: https://bugs.launchpad.net/bugs/2058573

Currently this patch is in the linux-next, will be in the unstable
kernel automatically.

[Impact]
In an oem project, we found the max playback volume of the headphone
is too high on 2 LG machines, it could bring harm to listeners. As
requested by OEM customer, we need to decrease the max volume.


[Fix]
Cherry-pick a mainline kernel patch, this could fix this issue.

[Test]
Booting with the patched kernel, plug the headphone, set the playback
volue to max, run:
amixer -c1 contents | grep -n2 "Headphone Playback Volume"

The value is 77,77 instead of 87,87 like below:
numid=1,iface=MIXER,name='Headphone Playback Volume'
  ; type=INTEGER,access=rw---R--,values=2,min=0,max=87,step=0
  : values=77,77


[Where problems could occur]
This patch changes the amplifier's default value, probably
will make the audio malfunction, but this change is specific
to those 2 LG machines (by SSID), will not bring regression
to other machines. For those 2 machines, we already tested patch,
the audio worked well.



Hui Wang (1):
  ALSA: hda/realtek: fix the hp playback volume issue for LG machines

 sound/pci/hda/patch_realtek.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

-- 
2.34.1