[linux-pm] [RFC][PATCH 00/11] Android PM extensions

[Uli Luckas]

On Monday, 2. February 2009, Alan Stern wrote:
> On Mon, 2 Feb 2009, Uli Luckas wrote:
> > Hi Alan,
> > we have had a (userspace) wake-lock implementation on our handyPC devices
> > for a couple of years now. So maybe I can shed some light.
> >
> > The above quote underlines pretty well, where Arve's and your ideas of
> > eraly-suspend and wake-locks diverge. And why you are missunderstanding
> > each other.
> > Arve is always talking about "blanking the screen" because that's what
> > the users sees. From the user's perspective the device is "suspended" as
> > soon as his user interfaces vanishes. That's probably also why his
> > notions of "suspend" and "wake" are not alway following a strict
> > definition.
>
> And that's partly why I have been complaining about the things he
> writes.  To a kernel programmer, "suspend" has a very specific meaning,
> quite different from what it might mean to a user.  When Arve posts on
> a kernel-oriented mailing list, he should use such words in a way his
> readers will understand.
>
Full Ack

> > If the device stays blanked while the user has his 10 min phone
> > conversation, then he won't even notice wether the device suspends or not
> > after the call. This is the idea. The user does not care for anything
> > they can't see.
> >
> > Arve is not talking about a laptop that needs to sleep befor it's
> > ventilation slot are covered. He is talking about a phone that could well
> > do with only blanking it's screen. Except it want's to save battery when
> > ever possible.
>
> The problem is that he's talking about making changes to a kernel that
> will be installed in all sorts of machines, from phones all the way up
> to supercomputers.  When you do this, you have to broaden your point of
> view -- your code has to run correctly in all of these settings.
>
Well, it should not interfere with any of these settings. And I think it is 
understood by now that we has to take back the semantic change of "echo mem 
> /sys/power/state"

On the other hand, I think it is quite reasonable to have aditional suspend 
mechanisms on a phone then you have on a super computer. Obviously you don't 
want the supercomputer to suspend everytime nobody is watching :-)

Uli


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Uli Luckas
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