Re: #12596 LOW 13.1.0: XO-4 sound streams hang over suspend/resume (was: [CL4] Movie Player can’t be closed.)

Zarro Boogs per Child bugtracker at
Mon May 20 17:30:10 EDT 2013

#12596: XO-4 sound streams hang over suspend/resume
           Reporter:  tomyin        |       Owner:  dsd          
               Type:  defect        |      Status:  new          
           Priority:  low           |   Milestone:  13.1.0       
          Component:  not assigned  |     Version:  not specified
         Resolution:                |    Keywords:               
        Next_action:  never set     |    Verified:  0            
Deployment_affected:                |   Blockedby:               
           Blocking:                |  

Comment(by dsd):

 I can't quite figure this one out.

 Firstly, the mmp-pcm offers flag  SNDRV_PCM_INFO_RESUME which suggests
 that it has complete suspend/resume handling. It doesn't - the
 suspend/resume code is commented out.

 Trying to enable the suspend/resume code: doesn't work. I suspect it is
 let down by the lack of suspend/resume routines in tdma. Attached as snd-
 debug.patch here.

 By dropping SNDRV_PCM_INFO_RESUME the stream will simply be fully stopped
 and restarted during suspend and resume, should be foolproof, and thats
 what we do on XO-1.75. However that doesn't work either. No tdma
 interrupts arrive when the stream is restarted during resume. I went to
 some extra steps to make sure that the right info is reprogrammed during
 resume, and I checked TDMA register dumps from just before enabling the
 DMA channel, no difference between the failing and working case. Attached
 as tdma-sr.patch here.

 Next step would be to check the ICU registers, make sure the interrupt is
 really unmasked, and look for other reasons why DMA interrupts would not
 be happening.

Ticket URL: <>
One Laptop Per Child <>
OLPC bug tracking system

More information about the Bugs mailing list