[maemo-users] brightness Re: [maemo-users] Re: Storage/Sleep Issues..

From: Igor Stoppa igor.stoppa at nokia.com
Date: Thu Jan 25 13:19:41 EET 2007
On Wed, 2007-01-24 at 17:34 +0100, ext Frantisek Dufka wrote:
> Karl Bellve wrote:
> > Igor Stoppa wrote:
> >>
> >> Power saving is not so important when the _energy_ wasted is so little
> >> and for an event which is supposed to happen very seldom (you don't turn
> >> off your device, don't you?).
> >>   
> > 
> > Every time it crashes! :-)
> > 
> > When using the Nokia at night, while watching TV in a dark room, the 
> > nokia can be absurdly bright during its reboot process. So bright, I 
> > have to face the nokia down on the couch while it reboots. So, the 
> > bright light is over whelming when you have the nokia set to its dimmest 
> > level because your eyes have adjusted to the dark.
> > 
> Exactly. That is my second (and maybe bigger) concern. Reboot or crash 
> at night is not a pleasant thing. While it is supposed to happen very 
> seldom in reality it is not such rare event. And the backligh really 
> does not consume significant power?
Check what i wrote, i wrote _energy_ and i'm gonna restate it: the
energy wasted by the backlighing durinig a device boot sequence is not
so much, when compared to other things that affect runtime power

Even 100 mA over less than 60 seconds are really nothing.
Otoh 2 mA over few days are _a lot_

> I thought it can be half of power 
> consumption on such devices. It was like that on ipaq 3870 I had. I 
> remeber something like 80mA when display off ~130mA minimum brightness 
> ~200mA full brightness, ~300mA full brightness + 100%CPU (not sure about 
> exact values, it is long time ago, it was available as file in /proc in 
> Familiar linux). On N770 I cannot check easily since some parts of power 
> management is ... guess what? There is this myth about hidden power 
> management ;-)
Nothinig prevents you from creating a sysfs entry wich returns 


or even a proc one, if you really are into that sort of thing.

> But anyway is there some real reason while the default cannot be much 
> lower until device boots to the point where user specified setting is 
> honored?
> Frantisek
No, just nobody so far had complained so much and from am effectiveness
standpoint, it's irrelevant to power saving.

Cheers, Igor

Igor Stoppa <igor.stoppa at nokia.com>
(Nokia M - OSSO /Helsinki Finland)

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