#9655 NORM 1.5-har: soft chirp when using USB devices

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#9655: soft chirp when using USB devices
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           Reporter:  pgf       |       Owner:  wad           
               Type:  defect    |      Status:  assigned      
           Priority:  normal    |   Milestone:  1.5-hardware-C
          Component:  hardware  |     Version:  1.5-B2        
         Resolution:            |    Keywords:                
        Next_action:  diagnose  |    Verified:  0             
Deployment_affected:            |   Blockedby:                
           Blocking:            |  
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Changes (by TMarques):

  * version:  not specified => 1.5-B2


Comment:

 I have found out that this screeching sound can be reproduced with an
 external USB SSD drive I have, the OCZ Solid 30GB, connected directly to
 the SSDs USB interface. The curious thing is it doesn't happen if I plug
 the SSD before I turn on the OLPC. If I boot and plug it in when it's in
 the XO OS, then it will immediately start buzzing a very high pitched
 sound and is always present when accessing the drive.
 This seems to happen for one reason: when buzzing the drive is detected as
 USB full-speed(1.1) only, instead of 2.0 and the transfer speed is stuck
 at around 483KB/s, give or take one KB/s.

 When in USB 2.0 mode, no buzz occurs at all and transfer speed is good at
 ~17MB/s.
 So far I haven't reproduced this behaviour with other USB drives but I'll
 look into some tomorrow.
 Will also upgrade the OS and firmware to check compatibility and
 availability of the USB 2.0 mode when hot-plugged but using USB 1.1
 devices seems the way to go towards identifying this.

 XO OS: build 64
 Firmware: Q3A25
 Hardware: unmodded B2

 I have noticed a less pronounced buzz happening, related to other use
 cases, but have yet to identify the cause - seems related to the speakers
 though.

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Ticket URL: <http://dev.laptop.org/ticket/9655#comment:5>
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