#1420 BLOC Trial-2: Audio driver for AD1888 - power verification.

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#1420: Audio driver for AD1888 - power verification.
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  Reporter:  jg           |       Owner:  cjb    
      Type:  enhancement  |      Status:  new    
  Priority:  blocker      |   Milestone:  Trial-2
 Component:  kernel       |     Version:         
Resolution:               |    Keywords:  power  
  Verified:  0            |  
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Comment (by cjb):

 Hi Jaya,

 > You would need to independently track whether the user wanted to record
 in a biased Mic mode (V_Ref on, LED on) or wanted to record in an unbiased
 /analog input mode (V_Ref off, LED off). It would not be correct for
 recording to always turn on V_Ref since that would break analog input
 mode.

 But we have a separate "analog input" mixer control that applications will
 toggle if they want to use analog in, so the above idea could work if we
 check the value of that control when deciding whether to turn on V_Ref as
 we start recording.  Might that work?

 > I think it'd be better to have the Recording LED driven by a gpio pin
 and have the driver turn it on when recording is started/stopped rather
 than making the Recording LED depend on V_Ref bias which is a property
 independent to recording state.

 The idea behind putting the LED in series with the V_Ref bias is that,
 even in the face of a totally compromised machine running an arbitrary
 kernel, you know if you're being listened to.

-- 
Ticket URL: <http://dev.laptop.org/ticket/1420#comment:17>
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