#12109 NORM 4-firmw: Audio on XO-4 under OFW sometimes sounds staticky

[Zarro Boogs per Child]

#12109: Audio on XO-4 under OFW sometimes sounds staticky
-------------------------------------------+--------------------------------
           Reporter:  wad                  |       Owner:  wmb at firmworks.com   
               Type:  defect               |      Status:  new                 
           Priority:  normal               |   Milestone:  4-firmware          
          Component:  ofw - open firmware  |     Version:  Development firmware
         Resolution:                       |    Keywords:  XO-4, OFW, audio    
        Next_action:  diagnose             |    Verified:  0                   
Deployment_affected:                       |   Blockedby:                      
           Blocking:                       |  
-------------------------------------------+--------------------------------

Comment(by wmb at firmworks.com):

 This turns out to be intertwined with the Linux driver!

 OFW normally turns off the audio system cleanly when it finishes an
 operation.  When it does so, the next audio operation turns the audio
 system back on cleanly, and there is no garbling.

 However, the audio driver has been patched for awhile so that it leaves
 the audio system on after the startup sound.  That is for the benefit of
 the old Linux driver, which does not know the byzantine recipe for turning
 on the audio island.

 I tried reinstating the "turn off" code into the OFW driver, and the
 symptom described above (which I could reproduce on my A2 quite easily)
 went away.

 Now that we have a Linux audio driver that know the audio island magic, we
 will eventually be able to restore the OFW driver to it's former (working)
 glory.

-- 
Ticket URL: <http://dev.laptop.org/ticket/12109#comment:1>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system