power management

David Pottage david at electric-spoon.com
Fri Jul 27 22:23:22 CEST 2007

On Friday 27 July 2007, Nelson Castillo wrote:
> On 7/27/07, Mark Eichin <eichin-openmoko at thok.org> wrote:
> > On an 850mAh nokia battery... maybe 3 hours mostly idle (not sure, I
> > came back to find it dead.)  Haven't timed it with the 1200mAh "real"
> > battery, but basically, "power management isn't really there yet."
> Is it hard to do it? Would using NO_HZ in the kernel help?

If you mean a tickless kernel, then probably if it where available. Last I 
heard it was only available for 32bit x86, not even x86_64 is supported.

In any case, I suspect the power saving stuff is more fundamental than that. 
From reading the Wiki, the Neo 1973 has a low power mode in which it goes to 
sleep, and turns of the screen, untill it receves and interupt from a device 
such as the GSM module or the touchscreen. The unfinished power management 
will be the necessary code to make the phone go to sleep after a minute or so 
of inactivity.

A tickless kernel might save a few more percent on top of that, but it is 
sleep mode you need to get from 3 hours battery life to 5 days.

David Pottage

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