[Trac #309] v20 EC breaks PS2 ports on atest.

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#309: v20 EC breaks PS2 ports on atest.
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 Reporter:  warp      |       Owner:  ray.tseng at quantatw.com
     Type:  defect    |      Status:  new                   
 Priority:  low       |   Milestone:  BTest-1               
Component:  hardware  |    Keywords:                        
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 Firstly, this is _only_ on atest, and as such my strong inclination is to
 request that we don't even look at this on Quanta's end until after B1 is
 done with, the EC works fine on btest and we simply can not afford to risk
 breaking that to try and fix atest at this date.

 Now, that said, at least the v20 EC used in OLPC-Q2A19 simply doesn't work
 on atest for PS2 port functionality.

 Judging from what I'm seeing my very best guess is that we're mangling
 some, but not all, outgoing PS2 commands to the AUX port.

 The replies we get back always seem to make sense, though a few times I've
 seen what might be bitflops, but with even vaguely heavy traffic it is
 quite clear that the touchpad simply isn't getting what we're sending,
 lots of 'that was a bad command' and 'please resend' replies.

 This behavior vanishes completely with the LaB and EC from build 91.

 If someone can point me at intermediate EC versions to try, with links to
 where I can get them, I'll be happy to try and pin down where it broke,
 but we definitely broke it on atest.

 But, again, no fix that even vaguely relates to this should touch what
 we're going to ship on B1, having that work is _far_ more important right
 now.

 Zephaniah E. Hull.

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Ticket URL: <http://dev.laptop.org/ticket/309>
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