#9415 HIGH Not Tri: SD write errors from Linux on XO 1.5

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#9415: SD write errors from Linux on XO 1.5
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           Reporter:  wad           |       Owner:  dsaxena    
               Type:  defect        |      Status:  new        
           Priority:  high          |   Milestone:  Not Triaged
          Component:  not assigned  |     Version:  1.5-A2     
         Resolution:                |    Keywords:  XO-1.5 SD  
        Next_action:  diagnose      |    Verified:  0          
Deployment_affected:                |   Blockedby:             
           Blocking:                |  
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Changes (by wad):

  * priority:  blocker => high


Comment:

 The hardware SD card problems appear solved by adding 33 ohm damping
 resistors to the SD_CLK, SD_CMD, and SD_DATA lines.   I took the four
 worst cases (laptops that couldn't complete a single ten MB writes without
 errors), ECO'd them, and have left them reading/writing all day without a
 single error.  The two original test machines running over 24 hrs. didn't
 show any errors either.

 Physically, this ECO requires removing all the solder from CON2 pins 9, 1,
 2, 7, and 8.  The pins are then carefully pried up with a very sharp
 X-Acto blade while heating the pad.  A 33 ohm resistor (SMD-0402 or 0603)
 is then soldered to the pad, and a wire run to the lifted pin.   On the
 top side of the motherboard, R130 (underneath and slightly north of the
 VX855) needs to be replaced with a 33 ohm SMD-0402 resistor.  Attemps at
 removing the SD socket to simplify the ECO are discouraged, as the socket
 (particularly the side tabs) is almost guaranteed to be damaged.

 I contend that there should be better error handling in the driver.  These
 errors were detected by the driver, and future writes to the device (from
 the same application) did work.  The device itself was undamaged (although
 if the writes occured while doing filesystem updates, the filesystem was
 corrupted.)

 Leaving this ticket open to reflect the needed code improvement.  An
 interested tester can contact wad in order to obtain a unmodified A2
 laptop which generates lots of the errors.

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Ticket URL: <http://dev.laptop.org/ticket/9415#comment:1>
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