#6670 BLOC Update.: Userspace (OHM) needs to know about the audio device state

[Zarro Boogs per Child]

#6670: Userspace (OHM) needs to know about the audio device state
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 Reporter:  cjb      |       Owner:  dilinger
     Type:  defect   |      Status:  new     
 Priority:  blocker  |   Milestone:  Update.1
Component:  kernel   |     Version:          
 Keywords:           |    Verified:  0       
 Blocking:           |   Blockedby:          
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 Specifically:

  * is the audio device open?
  * when (in epoch time, let's say) was the last time it was opened?

 We need to avoid suspending in the "device is open" case and the "device
 was open case", for two different reasons:

  1. Suspending while audio is active often breaks audio on resume.  This
 is #4247 and #6201.
  2. OHM currently doesn't avoid suspending when Record, Distance, eToys or
 the Totem plugin are busy with audio, because it doesn't know when those
 activities are currently using the mic/speakers.  Distance, for example,
 opens the audio device briefly in its "continuous measurement" mode, but
 is idle when not doing that.  The "when was the device last opened" will
 allow OHM to inhibit suspend for it.

 A sysfs interface to the two variables would be perfect.

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Ticket URL: <http://dev.laptop.org/ticket/6670>
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