Re: community PM requirements/issues and PowerOP [Was: Re: So, what's the status on the recent patches here?]

Matthew Locke
2006-09-11T19:30:12Z

I know its confusing having oppoint (from Dave Singleton) and powerop
being discussed at the same time. However, I believe we (PowerOP) have
already address most of the concerns/requirements from the community
and the embedded folks. Here is a summary of PowerOP that will
(hopefully) clear up our approach:

- PowerOP is only one layer (towards the bottom) in a power management
solution.
- PowerOP does *not* replace cpufreq
- PowerOP can replace the cpufreq_driver layer of cpufreq but cpufreq
integration not required.
- in kernel cpufreq governors are not directly affect by integrating
cpufreq and powerop. (Can be extended and/or ported to more
architectures and operating points)
- Again, cpufreq userspace and kernel interfaces can continue to be
used as they are today.
- PowerOP defines the parameters you want to change on a per
architecture/board basis.
- The PowerOP interface was discussed in detail on this list and we
haven't heard any negative comments.
- We are not advocating the integration with sleep states. We want to
get the PowerOP interface accepted and then we can build on it.
- PowerOP is *required* by the embedded folks.

We have a few more comments from Greg to take care of and we can add a
Documentation/ file. Then I think its time to get the PowerOP patches
in the queue for acceptance. Any comments about this?

btw, PowerOP<->Cpufreq integration discussion can wait until Dominik
and Dave Jones have time for more discussion.

On Sep 11, 2006, at 1:20 AM, Pavel Machek wrote:

> Hi!
>
> On Mon 2006-09-11 11:57:28, Eugeny S. Mints wrote:
>> [snip]
>>>> Are you arguing that the cpufreq interface be morphed to support
>>>> power
>>>> op applications?
>>>
>>> No. I'm arguing that
>>>
>>> * cpufreq interface should be used for changing cpu frequency
>> the patch set i sent out has cpufreq used for changing cpu frequency,
>> hasn't it?
>
> I was talking about kernel<->user interface.
>
> You did echo low > something to change CPU frequency, IIRC.
>
>> can we eventually start talking more close to the code rather than
>> speculating without it?
>
> Lets get kernel<->user interface right, first. You'll need to create
> Documentation/ entries for your interfaces, eventually, so lets do
> that, first, and then talk about code. Oh and it would be nice to cc
> lkml on that document, too. New kernel<->user interface is not
> decision taken lightly.
> Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures)
> http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
>