[Trac #186] Pre-BTest PS/2 port unreliable.

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#186: Pre-BTest PS/2 port unreliable.
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 Reporter:  warp      |        Owner:  ray.tseng at quantatw.com
     Type:  defect    |       Status:  new                   
 Priority:  blocker   |    Milestone:  BTest-1               
Component:  hardware  |   Resolution:                        
 Keywords:            |  
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Comment (by wmb at firmworks.com):

 I'll answer in order to get you going sooner, since the people who did the
 work are probably asleep.  I was listening in on IRC while they were
 discussing the issue, so I know a little about what they were doing.

 They were testing the AUX port without anything connected to it, by using
 the loopback feature.  The D3 command to the i8042 is supposed to cause
 the next byte to be inserted into the AUX port output register, even if
 there is nothing attached to the port.  That loopback feature was failing
 (and also attempts to use the real touchpad were failing).  I believe that
 the Linux driver depends on that loopback test as a sanity check for the
 driver startup.

 It is also possible simply to look at the value of EC register FC83 and
 verify that it has the wrong values.  According to the 3700 spec, the
 value "59" does not enable the D3 command, because the 0x20 bit is not
 set.

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Ticket URL: <http://dev.laptop.org/ticket/186#comment:9>
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