#12588 BLOC 4-softw: XO-4 max volume produces distortion

[Zarro Boogs per Child]

#12588: XO-4 max volume produces distortion
------------------------------------+---------------------------------------
           Reporter:  dsd           |       Owner:  dsd          
               Type:  defect        |      Status:  new          
           Priority:  blocker       |   Milestone:  4-software   
          Component:  kernel        |     Version:  not specified
         Resolution:                |    Keywords:               
        Next_action:  add to build  |    Verified:  0            
Deployment_affected:                |   Blockedby:               
           Blocking:                |  
------------------------------------+---------------------------------------
Changes (by dsd):

  * next_action:  never set => add to build


Comment:

 I have verified the DAC_VOL_2 and SPK_OUT_VOL registers compared to
 XO-1.75 where we don't see distortion. At max volume, the XO-1.75 actually
 lets DAC_VOL_2 run a tiny bit louder. The headphones are allowed to be run
 to the same max volume on both platforms.

 The difference is in the gain, specified in the general purpose register
 (40). I have reduced this on XO-4 from 7.40dB to 3.86dB, to match XO-1.75.
 Fixed in arm-3.5 f80b9e7.

-- 
Ticket URL: <http://dev.laptop.org/ticket/12588#comment:2>
One Laptop Per Child <http://laptop.org/>
OLPC bug tracking system