Power button behaviour

[Olivier Fauchon]

Andy Green wrote:
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> Somebody in the thread at some point said:
>
> | What is correct :
> |
> | 1/ There is no more power-management chip for hardware reset chip in
> | GTA02 ? Why ?
> | 2/ The kernel configures the power-management chip at boot, and then
> | only, the hardware reboot is working
> |
> | If 1 is true, does this mean it's not sure we can power off a zombified
> | kernel system ( ugly battery removal procedure )?
> | If 2 is true, can we  move the  power-management chip initialization in
> | bootloader so it works as soon as possible in boot sequence?
>
> The "PMU is boss of our boards" for both GTA01 and GTA02.  On the
> pcf50606 PMU in GTA01 as mwester said it listens out for button held and
> takes action itself.
>
> On pcf50633 on GTA02, whether it will listen for power button hold or
> not is determined by which "variant" you bought from NXP.  On the one
> that is closest to what we would want, it is told to not listen.  And
> unusually, that behaviour is not changeable over I2C at all, it is
> permanently and solely decided by which type you got from NXP.
>
> It means all we can do is partially synthesize the behaviour in the
> driver, which doesn't help if the CPU is crashed.
>
> There were only a couple of real choices about PMU variant, we made the
> best choice all things considered and this behaviour is a small breakage
> we have to accept to get the rest of the reasonable matches on other
> behaviour -- it isn't the only ding we have to take to balance heaven
> and earth with the PMU.
>
Thank you for your detailed answer, It's really interesting to 
understand all this P.M  design.

Olivier


> - -Andy
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-- 
Olivier Fauchon
Freelance System-Network Admin
Phone: +33 610 493 763
http://www.aixmarseille.com