aux button interrupt to pmu?

Andy Green andy at
Fri Jun 6 12:57:06 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
|> | Yes, I think this will have compatible issue if user don't have debug
|> | board for re-flash the NOR.
|> Can be, but we can maybe work around it.  For example we can look in
|> resume function of "keyboard" that deals with buttons to see if AUX is
|> still down when it resumes, and infer from this that we woke from AUX,
|> set the AUX resume reason bit right then.
| Difficulty is user usually don't count how many second they press on
| key, so the result come from user behavior will be un-predictable during
| resume. Like press too long/twice or more/too short/repeately suspend.
| User behavior is hard to predict even we only got 2 key in GTA02 :)

Well as Werner described, if AUX is only pressed for a few ms, something
BAD can happen and we crash.  But if it is pressed long enough to get
through steppingstone, then it is not critical if it is still held down
when Linux comes.  All that will happen then is we are not sure about
wake source, but we are still properly resumed and doing whatever it is
we were doing again.

|> Carsten mentioned it doesn't wake at the moment, I think it's probably
|> because it isn't enabled as wake source.  If it does wake through to
|> Linux OK from AUX -> NOR U-Boot -> Linux then the workaround above will
|> probably work for even current NOR U-Boot.
| I don't know if NAND and NOR have different init code, does this affect?

No need for it to affect anything, whether it does or not Werner can know.

Wake starts in U-Boot again like a cold reset, but very early if it sees
it is waking from suspend, it jumps to "magic address" of Linux resume
stuff in RAM that Linux stored into a special CPU register that survives
no core power.  So not much happens to be different during wake in
U-Boot path.  Still Werner is right logically there are two diverged
chunks of code there and logically they can differ for whatever reason.

|> Hardware design is a little bit older than this :-)
| Yup, we are doing software-able hardware ;)

Nobody told this to the guy that did the AUX key -> NOR design ;-)

- -Andy
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