[Trac #1381] EC startup unstable with game key depressed

[Zarro Boogs per Child]

#1381: EC startup unstable with game key depressed
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 Reporter:  wmb at firmworks.com    |       Owner:  David.Lin
     Type:  defect               |      Status:  new      
 Priority:  high                 |   Milestone:  BTest-3  
Component:  embedded controller  |    Keywords:           
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 I am trying to use the game keys to control Open Firmware startup.

 OFW will boot quickly from SD or NAND in the normal case where no game key
 is pressed.
 If the game key is pressed while powering up, OFW will probe the keyboard
 and the USB ports and offer the startup countdown for interactive use.

 The EC has a new command so OFW can poll the game keys very quickly.

 The problem is that the EC startup is unreliable if a game key is pressed
 before or soon after startup.

 I have seen several different symptoms of this, including:

 a) In some cases the system will start and run for about 2 or 3 seconds,
 then power off.

 b) In some cases, the system will hang when OFW tries to reset the
 wireless LAN using ports 381-383 to access the EC GPIOs.

 c) In some cases, the system will get to the point where OFW tries to read
 the game key state, but then will hang because the OBF bit never gets set
 after OFW writes 0 to port 68.

 If you wait until about 3 seconds after power-up before pressing the game
 keys, the startup works correctly.

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Ticket URL: <http://dev.laptop.org/ticket/1381>
One Laptop Per Child <http://laptop.org/>