[Trac #42] Audio driver for AD1888 - sensor input mode

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#42: Audio driver for AD1888 - sensor input mode
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 Reporter:  jg       |        Owner:  marcelo
     Type:  task     |       Status:  new    
 Priority:  blocker  |    Milestone:  BTest-1
Component:  kernel   |   Resolution:         
 Keywords:           |  
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Changes (by jg):

 * cc: Jaya, Kumar, <jayakumar.lkml at gmail.com>, mtosatti at redhat.com (added)
  * priority:  normal => blocker

Comment:

 Replying to [comment:5 marcelo]:
 > sensor input mode seems to be working from reports gathered, I haven't
 tested it myself though.


 Unless some code has magically written itself, the driver work is
 incomplete: Jaya Kumar wrote the Alsa control for analog input, but there
 is no support at a platform level to tell the EC (embedded controller) to
 disable/enable the capacitive input coupling.

 I had a significant conversation today with Jaya about how adding the
 platform specific code might be added to the AD1888 driver cleanly.  I
 suggest getting in contact with me/him to understand this issue fully.

 Fundamentally, there are three parts to this:
  * an Alsa control for the analog in (done by Jaya Kumar)
  * support for disabling the high pass filter that the AD1888 has in a
 previously unknown bit in an undocumented (before above) register. (this
 may or may not be implemented)
  * sending the EC a command to disable the capacitive input (not done).
 (definitely unimplemented).

 What I suggested to Jaya today, was that our OLPC platform specific code
 call an entry point passing in function pointers to functions that will
 control the embedded controller's interface to the capacitive input, and
 then the driver, if these pointers are not null, will call back into the
 platform specific code to implement the disabling/input of the capacitive
 input coupling.

-- 
Ticket URL: <http://dev.laptop.org/ticket/42#comment:6>
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