#1735 BLOC Trial-2: Audio clicking on resume.

[Zarro Boogs per Child]

#1735: Audio clicking on resume.
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  Reporter:  jg       |       Owner:  wad         
      Type:  defect   |      Status:  closed      
  Priority:  blocker  |   Milestone:  Trial-2     
 Component:  kernel   |     Version:  Build 406.14
Resolution:  fixed    |    Keywords:  power       
  Verified:  0        |  
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Changes (by wad):

  * status:  new => closed
  * resolution:  => fixed

Comment:

 Thanks to help from Analog Devices, the pop has been terminated.

 The solution is to depopulate C510, C511, C512, and C513.   These 100pF
 capacitors were present to prevent EMI, but also caused popping in the
 speakers.  If EMI is a problem, we can replace R436, R437, R438, and R439
 with ferrites.

 The pop is still heard from the open firmware "test /audio" routine.  This
 is due to a 30 mS delay between the deassertion of shutdown and the
 amplifier actually turning on. OFW starts playing a tone before this delay
 completes, causing an initial click.  The OFW commands "amplifier-on" and
 "amplifier-off", as well as alsamixer, click no more.

-- 
Ticket URL: <http://dev.laptop.org/ticket/1735#comment:34>
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