power management

[Gopi Palaniappan]

Hi:

    I have the same problem. There seems to be lot of information on the
olpc website but not easy to get to without spending time searching for it.
After a lot of searching and forgetting to bookmark and researching, I
decided to add the links of interest to me in my blog:
http://tags07.blogspot.com/2007/03/olpc-links.html
Feel free to refer to it.

On a different note, I'd like to work on PM user interface and perhaps also
on the kernel side.
I havn't dived into the hardware specs yet for OLPC. It would be nice to
have a wiki page with some basics to help ramp up the learning curve.
Some qns I have:
1. Does the hardware support Voltage/Frequency scaling?
2. What kind of sleep modes does it support?
3. Is there an infrastructure for power measurements? Do we have any current
drain measurements/readings?
4. Where are you experiencing the instability..is it at the hardware layer
or the syspend-resume mechanism?
5. Recently we did a lot of cleanup in the kernel to short-circuit the
default pm_suspend process, which has unnecessary layers that trumps the
suspends... the biggest one that comes to my mind is the dealing with
UNINTERRUPTIBLE SLEEP processes. I am not sure if you are experiencing
similar issues?
6. Is there a need for periodic wakeup? on mobile devices its required to
wakeup almost every minute to update clock display, battery level, rf
levels.it makes sense to sync up all these activities during the wakeup
period.I am not sure if a laptop has such a requirement..
7. Usually display/backlight is the biggest sucker of power.. do we use any
special displays that support partial refresh?
8. Suspend to RAM is good..it will give an "Instant-On" experience..is this
in the main kernel now or does it need special patches? If so where can i
find these patches?

I'd also like to discuss user interface APIs and useful features for a power
controller module in userspace. But i understand a stable suspend and resume
of devices should be the priority.


thanks,
Gopi







On 3/28/07, Jordan Crouse <jordan.crouse at amd.com> wrote:
>
> On 28/03/07 19:42 +0200, Jens Axboe wrote:
> > Hi,
> >
> > I'd love to help out with the power management and suspend/resume parts,
> > but so far I'm having trouble finding out what the status of it is,
> > goals, directions, etc. Did I miss a wiki page on this? If not, anyone
> > care to outline the current problems that need tackling?
>
> Once we get the core drivers working happily (graphics, DCON, USB, and
> CaFE NAND), then we'll be ready to be more organized with wiki pages, and
> images and such.  Following working core drivers, our emphasis will shift
> to the fringe drivers.
>
> My personal target is to survive 1000 consecutive suspend/resume cycles
> with a full system running a nominal load (sugar, nominal
> CPU load + network).  If we accomplish that, then I think we'll be ready
> for
> anything they throw at us.
>
> After that we'll shift our attention to optimization, but I would
> like to stress that at this point, stability trumps speed any day of the
> week and twice on Sunday.
>
> Jordan
>
> --
> Jordan Crouse
> Senior Linux Engineer
> Advanced Micro Devices, Inc.
> <www.amd.com/embeddedprocessors>
>
>
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>
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