#8324 BLOC 8.2.1: WLAN device disappears permanently

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#8324: WLAN device disappears permanently
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 Reporter:  wad            |         Owner:  dwmw2        
     Type:  defect         |        Status:  new          
 Priority:  blocker        |     Milestone:  8.2.1        
Component:  wireless       |       Version:  not specified
 Keywords:  WLAN libertas  |   Next_action:  diagnose     
 Verified:  0              |     Blockedby:               
 Blocking:                 |  
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 We have been having a significant number of motherboards in the field
 which stop communicating with their WLAN module.  These all worked fine,
 sometimes for months, then suddenly refused to find the WLAN module when
 enumerating the USB bus.   Once this occurs, the device does not reappear,
 even after power-cycles, full system reset, etc.

 These are production (C2) laptops.   It is unknown if it also happened on
 earlier motherboards.

 This is confirmed to occur on all laptop builds between 656 and 703.  It
 might also be happening on earlier and later builds.

 I started diagnosing one of these laptops by disconnecting the USB
 connection between the Southbridge and the WLAN module, attaching a USB
 cable to the module, and testing if it would work on another USB port (or
 even another laptop).  The device was still not found.

 I quickly checked that the WLAN processor was running -- operating
 voltages were fine and I could see it fetching data from it's serial
 flash.

 Next, I swapped the serial flash with a serial flash from a working
 machine.  This corrected the problem !

 I read the data off the flash device that wasn't working -- it is attached
 to this ticket.

 There is a slight possibility that it was the heating of the WLAN module
 to remove the serial flash that corrected the problem, and not the actual
 change of flash.

-- 
Ticket URL: <http://dev.laptop.org/ticket/8324>
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