#10632 NORM Not Tri: USB failure when updating SD using OFW

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#10632: USB failure when updating SD using OFW
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 Reporter:  wad                  |                 Owner:  wmb at firmworks.com
     Type:  defect               |                Status:  new              
 Priority:  normal               |             Milestone:  Not Triaged      
Component:  ofw - open firmware  |               Version:  1.75-A2          
 Keywords:  XO-1.75              |           Next_action:  never set        
 Verified:  1                    |   Deployment_affected:                   
Blockedby:                       |              Blocking:                   
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 On many if not all 1.75 A2 motherboards, an attempt to use fs-update to
 update the internal/external SD or eMMC will result in a "Short read of
 zdata file" error message from OFW.

 The crashing usually happens either around block 50 or around block 1200.

 This was tested running OFW version Q4A10i.   On motherboards that have
 shown this failure, running a wear-levelling test from Linux on the USB
 device doesn't find any errors.

 I spent some time looking at the power rails (Vmain, +3.3V, +5V_USB, Vin).
 There doesn't seem to be any abnormal activity when OFW fails.   The
 voltage spikes due to the Vmain power supply switching transient are
 slightly larger when running OFW fs-update than when running the Linux
 tests, but successful efforts to reduce the spikes didn't have any effect
 on the frequency of crashing.

 Increasing the voltage of Vmain to 1.35V from 1.25V didn't have any effect
 on the crash frequency.

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Ticket URL: <http://dev.laptop.org/ticket/10632>
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