#9423 NORM 1.5-fir: Stabilize OFW USB handling on XO-1.5

[Zarro Boogs per Child]

#9423: Stabilize OFW USB handling on XO-1.5
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           Reporter:  wmb at firmworks.com    |       Owner:  wmb at firmworks.com
               Type:  defect               |      Status:  reopened         
           Priority:  normal               |   Milestone:  1.5-firmware     
          Component:  ofw - open firmware  |     Version:  1.5-B2           
         Resolution:                       |    Keywords:                   
        Next_action:  diagnose             |    Verified:  0                
Deployment_affected:                       |   Blockedby:                   
           Blocking:                       |  
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Comment(by wmb at firmworks.com):

 I have a simple recipe for triggering the USB problem. This recipe
 causes the timeout on several different USB storage devices from
 different vendors.

 Here is the recipe to use for the demo board:

 * Put a large - several hundred megabytes - file on a FAT-formatted USB
 stick. I am using "os48.zd", which is an OLPC OS image, but I'm pretty
 sure that the contents of the file don't matter.

  ok select u:\os48.zd
  ok 0 begin dup . (cr 1+ 100000 4000 read drop key? until

 (On OLPC running Q3A18, you would first need to type "no-usb-delay" to
 disable the workaround that masks the problem. On the demo board, that
 should not be necessary, because the OFW I gave you for the demo board
 does not have the workaround code.)

 Here is a slightly simpler version of the last line, containing only the
 crucial steps:

  ok begin 100000 4000 read drop again

 The more-complicated version also displays a running count of the number
 of reads, and lets you interrupt the process by typing a key. Either
 version should fail. In my tests, the failure happens in about 1 second.

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Ticket URL: <http://dev.laptop.org/ticket/9423#comment:17>
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