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List:       linux-arm-kernel
Subject:    Re: Arm linux software suspend
From:       Paul Schulz <pschulz01 () gmail ! com>
Date:       2005-08-08 13:55:45
Message-ID: cc9bf44d050808064971eb3e28 () mail ! gmail ! com
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Hi Abhijit,

I have a similar issue, on a PXA255. I would like
to suspend to NAND flash. The reason?

The device is to be part of a machine, and
as well as the restore-from-disk (hopefully) being 
faster that a cold-start, all settings and
configurations will be (trivially) maintained
between 'sessions.

(There is also going to be a power fail detect to
trigger the suspend-to-disk.)

So, I'm keen to hear how you get on. 

Paul

On 8/6/05, Abhijit Bhopatkar <bainonline@gmail.com> wrote:
> 
> On 8/5/05, Nicolas Pitre <nico@cam.org> wrote:
> > On Fri, 5 Aug 2005, Geoff Levand wrote:
> >
> > > Holger Schurig wrote:
> > > >>I am trying to figure out a powersaving scheme for an embedded 
> device. And
> > > >>was wondering if we can do a complete hibernate on arm-linux.
> > > >
> > > >
> > > > # echo mem >/sys/power/state
> > > >
> > > > works quite nice here (Kernel 2.6.13-rc2, Intel PXA255).
> > > >
> > >
> > > That will get you suspend to ram. He wants suspend to disk (echo disk
> > > >/sys/power/state).
> >
> > You are sure that's what he wants?
> :-)
> Well he is right
> I want suspend to disk, so that i can completely shutdown the board.
> Of course i will have to replace the actual disk with something else
> like perhaps a usb partition (may be too slow but it doesn't matter).
> Or i will have to write a new back end, but before i dive into
> exploring that, i just wanted to know if suspend to disk is possible
> on arm?
> 
> I am using a custom board with PXA255, and a wifi card attached to
> pcmcia, (i don't need wifi to be preserved so i can always unload the
> modules before hibernating.) Yes i have external means of turning the
> board off and on again.
> The problem i am tackling is that, the main application running takes
> a long time to initialise, something like 10 mins. on each reboot.
> That makes it shutting it down in the middle, almost impossible. I can
> do with 1-2 mins of boot time though, i guess that's more than enough
> to wake up from hibernation for a system with 32 MB ram.
> The device is not needed to be up all the time and is kept up only due
> to init latency.
> (don not ask me why it takes 10 mins. i am already frowning at the app
> developers)
> 
> Thanks and regards,
> Abhijit Bhopatkar
> 
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