#10901 BLOC 1.75-fi: XO-1.75 A3 fails to boot OFW

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#10901: XO-1.75 A3 fails to boot OFW
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           Reporter:  wad       |       Owner:  wad          
               Type:  defect    |      Status:  new          
           Priority:  blocker   |   Milestone:  1.75-firmware
          Component:  hardware  |     Version:  1.75-A3      
         Resolution:            |    Keywords:  1.75         
        Next_action:  diagnose  |    Verified:  0            
Deployment_affected:            |   Blockedby:               
           Blocking:            |  
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Comment(by wad):

 At this time, I believe this might be two different problems and am
 debugging it as so.  In Cambridge we have two boards which won't boot
 unless they have elevated Vcore voltages: #5 boots at 1.425 and #32 boots
 at 1.395V.

 We also have three boards which won't boot reliabily the first time.
 After the SOC has been powered for thirty seconds or so, they boot
 reliably with default Vcore (nominally 1.345V).   These are #1 (1.345V),
 #14 (1.350V), and #22 (1.345V -- measured at the SoC).

 Cooling the SoC slightly allows this problem to be reliably reproduced.
 Raising Vcore on these boards makes them boot reliably.   #1 boots
 reliably at 1.425V.

 In contrast, a working board (#3) runs with a Vcore range of 1.330V to
 1.360V, but doesn't work at 1.380 or 1.40V.

 Attempts to read fuse block three from the sercurity processor to
 determine the voltage profile of the SoC reads all zeroes for that fuse
 block --- using the same access mechanism which allows us to read fuse
 blocks 1 and 2.  This either indicates that we don't know how to read fuse
 block three, or that Marvell wasn't correct when they told us these parts
 were fully tested and voltage profiled.

-- 
Ticket URL: <http://dev.laptop.org/ticket/10901#comment:6>
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