Accelerometer question

Rui Miguel Silva Seabra rms at
Fri Oct 10 12:52:35 CEST 2008

On Fri, Oct 10, 2008 at 08:33:19AM +0100, Andy Green wrote:
> Rui Miguel Silva Seabra wrote:
> > 	The rate at which they feed me data only starts up when the file
> > 	handle is opened, and stops when it's closed?
> This is the case, the interrupts are quenched when no file handles are
> open on them.

The interrupts are quenched, but is it still draining battery life?

> > I'm just wondering, because my 1 year old Nokia 2670 just lasted a whole
> > week in idle on an 700mAh battery, and OpenMoko lasts only about 8/9
> > hours in idle with a 1200mAh battery. It is nuts, we all know that, but
> > I'm more interested right now into extending battery life, as it is my
> > single greatest problem with OpenMoko right now.
> The issue is "what does idle mean".  Suspend for Freerunner should last
> a week.  Sitting there with CPU up even with backlight down is 60-90mA
> on battery, suspend is 5 - 10mA and that's why you get battery life
> reduced accordingly if you stay out of suspend.  That's a kernelspace
> issue on the one hand (suspend is not entirely reliable) but also a
> userspace issue (there have been bugs negotiating entry to suspend
> instead of sitting there with CPU up at 400MHz and backlight down).

AFAIK (which isn't that much really) this old Nokia phone does not
actually suspend (or if it does it's mindbloggingly fast on recovery).

5-10 mA would mean at worse case about 5 days. That would be very much
acceptable in terms of usage, but sill very low... it would last that
long in suspend because it's a 1200mAh battery! :)

Anyway suspend is definitly not reliable :) which I suspect in great
part has to do with the blasted NDA over the graphics card documentation.

Remember the White Screen of Death?

Maybe OM inc guys need help with the X driver, but since it's not on
their priority, suspend will hardly work reliably anytime soon... I fear


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+ Whatever you do will be insignificant,
| but it is very important that you do it -- Gandhi
+ So let's do it...?

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