#3813 HIGH Untriag: Add a delay to mic recording.

[Zarro Boogs per Child]

#3813: Add a delay to mic recording.
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 Reporter:  cjb     |       Owner:  cjb      
     Type:  defect  |      Status:  new      
 Priority:  high    |   Milestone:  Untriaged
Component:  kernel  |     Version:           
 Keywords:          |    Verified:  0        
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 Ben Schwartz reports that, at the moment, approximately the first 4000
 samples (~100ms) of every microphone recording are contaminated with a
 full-range pop, as a consequence of recording while the offset is still
 stabilizing after the mic bias is applied.

 Ben says that the nastiest (negative) part of the pop is over after about
 30 samples, but it takes the rest of the 4000 for the DC bias to
 equilibrate.

 Mitch and Ben suggest trying a 50ms delay inbetween bias on and recording,
 seeing if there's an audible click present in the recording, and halving
 the delay and trying again if not.  I suggest doing this in
 snd_cs5535audio_capture_open(), which is the kernel function that applies
 the mic bias.

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Ticket URL: <https://dev.laptop.org/ticket/3813>
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