Power management concept...

Harald Welte laforge at openmoko.org
Thu Apr 19 13:20:14 CEST 2007

On Thu, Apr 19, 2007 at 11:05:51AM +0200, Nils Faerber wrote:
> 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 ;)

well, I'd actaully rather spend time on the implementation than to
preemptively talk about vapor that doesn't exist...

the wiki page explicitly distinguishes between PMU and CPU power states
that 'theoretically' exist, and the 'system power states' that we have
introduced for our actual use by system-level power management.

> So, do you want to actually use slow_mode instead of any real sleep
> modes with SDRAM in self refresh, correct?

yes, that is already there. you can completely suspend to
self-refreshing SDRAM and resume from that.  Even the P0 phonse can do

> 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.

no, unfortuantely 'power-off' mode is how samsung calls their 'suspend
to sdram' mode.  That's once again a reason for the above wiki page to
use and define state names and to translate between the various vendor
state names and human readable language.
- Harald Welte <laforge at openmoko.org>          	        http://openmoko.org/
Software for the world's first truly open Free Software mobile phone

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