Starting point: Suspend to RAM on embedded devices?

Starting point: Suspend to RAM on embedded devices?

[Wappler Marcel]

Hi all,

I am looking for ways to let an ARM9 based embedded device running Linux go to a "suspend to RAM" like mode. In my opinion this
could enable a HIFI equipement like "power-off" and "power-on" feeling with quick response (less than 2 seconds) and much less power
consumption in the standby mode than during normal operation.

- Is there public available documentation about APM like features on ARM architectures?
- Is there a mainstream Linux platform (best if also ARM9 based) which has achieved this already?
- I am also interested in experiences with applications running on such platforms, 
  trigger like systems which inform the apps and so on...

Thank you Marcel
(please CC me on replay)
--
Marcel Wappler
Bridgeco AG
CH-8600 Dübendorf
Switzerland

Re: Starting point: Suspend to RAM on embedded devices?

[Wander Winkelhorst]

On Thu, Apr 10, 2008 at 10:14 AM, Wappler Marcel
<Marcel.Wappler@bridgeco.net> wrote:

>  - Is there a mainstream Linux platform (best if also ARM9 based) which has achieved this (a "suspend to RAM" like mode.) already?

The TomTom portable navigation devices (TomTom one, TomTom go etc.) do this.
They are based around an ARM CPU from Samsung and run Linux. If you
press the "power button" it actually does a suspend-to-ram.
They use a somewhat custom linux kernel, the source is available on
their website, www.tomtom.com/gpl
There is a website that aims to run open source software on the tomtom
(ie. not the tomtom navigation software) on http://www.opentom.org

Hope this helps,

Wander

RE: Starting point: Suspend to RAM on embedded devices?

[Wappler Marcel]

Wander Winkelhorst wrote:
> The TomTom portable navigation devices (TomTom one, TomTom go etc.)
> They are based around an ARM CPU from Samsung and run Linux. If you
> press the "power button" it actually does a suspend-to-ram. 

Do you have (or anybody else) experience, how long the wakeup from suspend to RAM does take? Would it be possible to have the fully
functional device with running aplication one second after pushing the power button?

regards,
Marcel

Marcel Wappler
Bridgeco AG
CH-8600 Dübendorf
Switzerland

Re: Starting point: Suspend to RAM on embedded devices?

[Wander Winkelhorst]

On Thu, Apr 10, 2008 at 11:53 AM, Wappler Marcel
<Marcel.Wappler@bridgeco.net> wrote:
> Wander Winkelhorst wrote:
>  > The TomTom portable navigation devices (TomTom one, TomTom go etc.)
>
> > They are based around an ARM CPU from Samsung and run Linux. If you
>  > press the "power button" it actually does a suspend-to-ram.
>
>  Do you have (or anybody else) experience, how long the wakeup from suspend to RAM does take? Would it be possible to have the fully
>  functional device with running aplication one second after pushing the power button?

Well, my tomtom one V2 takes a couple (5-10) of seconds to wake up
again. but that time includes reinitialising the bluetooth chip,
checking the SD card, restarting the GPS, loading AGPS data and
resuming the navigation software. If you don't have to do all those
things it would probably resume a lot faster.

RE: Starting point: Suspend to RAM on embedded devices?

[Wappler Marcel]

Wander Winkelhorst wrote:
> Well, my tomtom one V2 takes a couple (5-10) of seconds to wake up
> again. but that time includes reinitialising the bluetooth chip,
> checking the SD card, restarting the GPS, loading AGPS data and
> resuming the navigation software. If you don't have to do all those
> things it would probably resume a lot faster.    

So Wander,

I had a short look in to the opentom.org project and have got a lot of new questions:
- does the opentom.org kernel support the original "suspend to RAM" functionality of TomToms kernel?
- is there anybody using this functionality?
- has somebody measured the power consuption in the sleep mode?
- the opentom kernel has a file "/arch/arm/kernel/apm.c" which is not in the normal Linux kernels. Where comes this file and other
power saving infrastructure from, where can I grab it, is there anyone else out there using it, on which device?


Thanks,
Marcel

Marcel Wappler
Bridgeco AG
CH-8600 Dübendorf
Switzerland

Re: Starting point: Suspend to RAM on embedded devices?

[Wander Winkelhorst]

On Thu, Apr 10, 2008 at 3:04 PM, Wappler Marcel
<Marcel.Wappler@bridgeco.net> wrote:
> Wander Winkelhorst wrote:
>  > Well, my tomtom one V2 takes a couple (5-10) of seconds to wake up
>  > again. but that time includes reinitialising the bluetooth chip,
>  > checking the SD card, restarting the GPS, loading AGPS data and
>  > resuming the navigation software. If you don't have to do all those
>  > things it would probably resume a lot faster.
>
>  So Wander,
>
>  I had a short look in to the opentom.org project and have got a lot of new questions:

I can't anwser all of these questions, I'm not a part of the opentom
project. If you want to ask more questions to the people who are,
plase ask on the opentom mailing list.

>  - does the opentom.org kernel support the original "suspend to RAM" functionality of TomToms kernel?
I don't know, but IMHO it doesn't matter, because you can just use the
TomTom kernel.

>  - is there anybody using this functionality?
The Opentom project is a bit... quiet...

>  - has somebody measured the power consuption in the sleep mode?
With the TomTom provided kernels, the power consumption is next to
nothing. These devices are powered by a small battery, yet can stay
suspended for weeks.

>  - the opentom kernel has a file "/arch/arm/kernel/apm.c" which is not in the normal Linux kernels. Where comes this file and other
>  power saving infrastructure from, where can I grab it, is there anyone else out there using it, on which device?
I don't know, sorry.

Wander.

Re: Starting point: Suspend to RAM on embedded devices?

[Pavel Machek]

On Thu 2008-04-10 10:14:30, Wappler Marcel wrote:
> Hi all,
> 
> I am looking for ways to let an ARM9 based embedded device running Linux go to a "suspend to RAM" like mode. In my opinion this
> could enable a HIFI equipement like "power-off" and "power-on" feeling with quick response (less than 2 seconds) and much less power
> consumption in the standby mode than during normal operation.
> 
> - Is there public available documentation about APM like features on ARM architectures?
> - Is there a mainstream Linux platform (best if also ARM9 based) which has achieved this already?

Sharp zaurus, olpc, nokia n810...

And yes, suspend/resume is quite fast, ~2sec on zaurus, 300msec on
olpc.

-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html