power management

[Jens Axboe]

On Wed, Mar 28 2007, Chris Ball wrote:
> Hi Jens,
> 
>    > 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?
> 
> Almost everything's happening on IRC at the moment.  We're still working
> on having our display controller resume properly -- we have a novel
> resume strategy which is that the display controller has RAM to keep 
> the screen displaying while the CPU is asleep, so that we can go to S3
> anytime the user isn't typing or running something on the CPU.  The
> wireless stays on (forwarding packets) in S3, too.  
> 
> We aren't using ACPI, because we want as much control over our 
> suspend/resume time as possible, and because we already know
> everything about the hardware -- it's no use being able to go
> to sleep between keystrokes if it takes so long to do so that 
> the user realises it's happening.  I'm sure there'll be work both
> specific to OLPC and generic to Linux involved in getting suspend
> and resume as fast as they can be.
> 
> Hope that makes sense as a set of goals; once we have the base 
> drivers resuming as well as the kernel, I think it'll be time to 
> provide documentation on the wiki for easy steps to upgrade to a 
> build with our kernel patches.  That should happen shortly.

Yep makes sense as a higher level overview, that much I'm pretty much on
top of already. Probably my question was as clear as it should be, what
I'm wondering is what the higher level overview of the missing lower
level bits (hope that makes sense :-) are atm? Things like "USB foo
doesn't restore properly" and similar issues of that nature.

I tried the olpc-pm 'test' mode and it seems to work for me, whereas the
'normal' mode hangs hard when I'm expecting it to shutdown the machine.

-- 
Jens Axboe