#9604 NORM 1.5-sof: build DC sensor mode on audio driver

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#9604: build DC sensor mode on audio driver
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           Reporter:  Quozl     |       Owner:  dsd              
               Type:  defect    |      Status:  new              
           Priority:  normal    |   Milestone:  1.5-software-beta
          Component:  kernel    |     Version:  not specified    
         Resolution:            |    Keywords:                   
        Next_action:  diagnose  |    Verified:  0                
Deployment_affected:            |   Blockedby:                   
           Blocking:            |  
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Changes (by Quozl):

  * next_action:  test in build => diagnose


Comment:

 Retest with XO-1.5 B2 q3a18 os51.

 I was unable to establish any relationship between the values read by
 arecord and the voltage or current supplied to the microphone input by me.

 The XO-1.5 microphone input appeared to be a short.  I applied a current
 limited source to the bare ends of a 3.5mm mono plug, and measured the
 voltage.  The voltage was good (0.366V) with the plug disconnected from
 the XO, but always went zero when the plug was inserted.  No changes to
 alsamixer controls made any difference.

 The XO-1 microphone input on the other hand caused the voltage to decline
 only slightly (0.366V to 0.344V).  Again with a 3.5mm mono plug;
 Tip/Sleeve.

 Substituting a 3.5mm stereo plug; Tip/Ring/Sleeve, measured a voltage
 emitted by the XO-1.5 microphone socket; 0.15V normal, 1.7V while
 ''arecord'' runs, which persists for five to six seconds after ''arecord''
 terminates before the voltage returns to 0.15V.  Muting and unmuting the
 master volume control in alsamixer also causes this.  A voltage of 2.6V
 could be obtained by switching on the ''DC Mode Enable'' and raising to
 ''DC Input Bias'' to 80%, then a few seconds later it would return to
 0.15V.

 Attaching the current limited source, the readings were consistent with
 the two voltage sources (XO-1.5 and my external source) being combined.

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Ticket URL: <http://dev.laptop.org/ticket/9604#comment:11>
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