[maemo-developers] Internet Tablet Power Management presentation from linux-pm summit 2007

From: Andrew Flegg andrew at bleb.org
Date: Wed Jul 11 15:44:58 EEST 2007
On 7/11/07, Igor Stoppa <igor.stoppa at nokia.com> wrote:
> On Wed, 2007-07-11 at 13:28 +0100, ext Andrew Flegg wrote:
> >
> > This being reraised made me think about why, the other day, I *did*
> > want user suspend. Sometimes I just want a quick way to:
> >
> >   * Shut off all network connections.
> >   * Stop any noise (except configured alarms)
> >   * Have the screen locked
> >   * Not have to save my position
> >   * Be able to resume quickly
> >
> > This isn't "suspend" in a power sense, but in a use-case sense the
> > purpose is clear.
> Why not just put it in offline mode and lock the screen and keys?
> That's what i do and it simply works.

Well, that doesn't block sound so if the battery starts going down in
the night, or similar, I could be awoken by a noise. It's also clumsy
as the sequence is:

   1) Press power button
   2) Select offline mode
   3) Press OK
   4) Press power button
   5) Press OK

Unlocking is a simlar number. That's not exactly a simple sequence, as
say the 770's cover was (as Andy Mulhearn points out).

Now, if it was possible to hook into the power menu to define my own
sequence of actions I could set up a "turn off volume", "go offline",
"lock screen & keys" function and map that to the top-most item.

Is that possible? I've not seen any documentation on
/etc/systemui/systemui.xml except for hacking it to re-enable
soft-poweroff and reboot.

> The only drawback is that with sane applications you would get "only" 12
> days with a full battery.

As you point out elsewhere though, the only "sane" applications we can
be sure of are the IT OS built-in ones, at the moment :-(

> I do admit that in some extreme case it might not be enough, but on
> OMAP2 it doesn't justify the hassle.

As I said, when users say "suspend" they mean the kind of thing I
describe above, what that maps to under the covers is not important.

> I'd rather spend time and resources in fixing kernel and applications to
> make sleep while idle as close as possible to suspend to ram.

Agreed. But hopefully the system is open enough to allow third parties
to hook into the infrastructure (e.g. power menu).

> Plain suspend to ram (or disk), imho, sucks, because it produces a
> useless brick till it is forcibly resumed. I think it would be much
> better to simply let wakeup events happen, but make sure that only the
> _useful_ ones happen.

Absolutely. FSVO "useful".

> The user should be able to configure wakeup sources, certainly, even up
> to the point of saying: wake up only for power button, but the system
> should manage itself automatically.

Agreed, remember I'm talking about use-case for users, not if it's an
*actual* system suspend under the covers.



Andrew Flegg -- mailto:andrew at bleb.org  |  http://www.bleb.org/

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