Power management concept...

Nils Faerber nils.faerber at kernelconcepts.de
Thu Apr 19 12:57:12 CEST 2007

Nils Faerber schrieb:
> Harald Welte schrieb:
>> On Tue, Apr 17, 2007 at 04:58:49PM +0200, Nils Faerber wrote:
>>> This is maybe slightly off-topic concerning hardware but anyway, what is
>>> the power management concept planed for the NEO?
>> Does 
>> http://wiki.openmoko.org/wiki/Neo1973_Power_Management
>> help you a bit?
> A bit, yes, this describes what is possible, I guess.
> What I was more curious about is how you actually intend to use it ;)
> So, do you want to actually use slow_mode instead of any real sleep
> modes with SDRAM in self refresh, correct?
> That would mean that if the phone is sitting idle in my pocket the CPU
> will be put in slow mode as least power consuming mode, correct?
> Off-mode will then really be off, like in power off.

Oh, and maybe adding, how will the modes be accesible through Linux?
Will the device automtically go into slow mode when idle or will some
userspace application have to decide that it is idle enough and put the
device in slow mode?

And if userspace, there is already /sys/power/state, will it be
controllable through this interface? Something like slow mode, if I
understand the function of the mode correctly, is not yet "supported"
(or rather thought of) for the power/state interface. Though I
personally think it would be pretty neat!

If I get this right, the device will operate almost normally in slow
mode, but just - err - slow ;) That would really be very cool! You could
do a lot of things in there. In that case I would also not like the idea
very much of some automatic idle detection. There could be use cases
where we definitely want to use all computation power that is still
available in slow mode but not auto-put the device back in normal mode -
like the touchscreen guesture to unlock the device.

  nils faerber

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