For the quiet and non-quiet problem, since there is no difference between 1st 
and 2nd alsa-info.txt, I really have no idea what is the root cause for this 
problem. Probably, we can do another test:
don't plug the headphone in poweroff state,
poweron the machine, and let machine enter grub, then plug the headphone, after 
that, let machine boot linux kernel..., let us see if the headphone is still 
quiet or not, if not, it looks like bios do sth if plugging headphone in 
poweroff state.


For the noise problem, since I did not hear the noise in my test two weeks ago, 
and I don't have machine in my hand now, I need to wait for ending of holiday 
(after new year holiday), then I will get the machines and redo the test.

thanks.

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https://bugs.launchpad.net/bugs/1805079

Title:
  click/pop noise in the headphone on several lenovo laptops

Status in linux package in Ubuntu:
  Fix Committed

Bug description:
  [Impact]
  Lenovo told us that some linux uers reported headphone noise on Lenovo's
  website. After investigating, we found those Lenovo laptop mdoels all
  have the codec of alc285, and we can reproduce the noise problem too.

  [Fix]
  Don't use the DAC of headphone, let headphone share the DAC with speaker,
  the noise disappears.

  [Test Case]
  After applying this patch, we tested on Lenovo P52, P72, X1 carbon and X1
  Yoda2, no noise anymore

  [Regression Potential]
  Low. This patch only apply to several lenovo machines, and after applying
  this patch, both speaker and headphone still work very well.

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