Re: [patch] pm: fix runtime powermanagement's /sys interface

Pavel Machek
2006-01-05T23:05:56Z

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On Čt 05-01-06 17:55:33, Preece Scott-PREECE wrote:
> I shouldn't oversimplify the power management in a cell phone. When I said we turned whole devices on/off, I was referring only to what the system-level PM (which uses suspend/resume) does. There's a fair amount of subsystem-specific power management outside the Linux suspend/resume framework. Some of it might be handled in the framework, if the framework were more capable.
>

Ok, system-level PM is not interesting in this discussion.

You do runtime-powermanagement of devices, right? Let's take display
as an example.

(1) Do you have multiple display states like

on-fast: can refresh image every 10msec

on-slow: can only refresh image once per second, but takes less power

?

(2) Do you have multiple display states like

off-fast: display is off, user can not see anything, but it only takes
msec to wake up

off-slow: it takes 1 second for display to wake up, but it takes less
power

?

[Maybe display is bad example, but I can't think of better device with
complex power management]

Pavel

> scott
>
> -----Original Message-----
> From: Pavel Machek [mailto:pavel@ucw.cz]
> Sent: Thursday, January 05, 2006 4:46 PM
> To: Preece Scott-PREECE
> Cc: Alan Stern; akpm@osdl.org; linux-pm@lists.osdl.org; linux-kernel@vger.kernel.org
> Subject: Re: [linux-pm] [patch] pm: fix runtime powermanagement's /sys interface
>
> On Čt 05-01-06 17:21:38, Preece Scott-PREECE wrote:
> > We do have multiple system-level low-power modes. I believe today they
> > differ in turning whole devices on or off, but there are some of those
> > devices that could be put in reduced-function/lowered-speed modes if
> > we were ready to use a finer-grained distinction.
>
> I think we were talking multiple off modes for _single device_. It is good to know that even cellphones can get away with whole devices on/off today.
> Pavel
>
> --
> Thanks, Sharp!

--
Thanks, Sharp!