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

Eugeny S. Mints
2006-09-11T20:53:46Z

Pavel Machek wrote:
> Hi!
>
>> I know its confusing having oppoint (from Dave Singleton) and powerop
>> being discussed at the same time. However, I believe we (PowerOP)
>> have
>
> Yes, it is.
>
>> - PowerOP is only one layer (towards the bottom) in a power management
>> solution.
>> - PowerOP does *not* replace cpufreq
>
> PowerOP provides userland interface for changing processor
> frequency. That's bad -- duplicate interface.
Basically the biggest problem with cpufreq interface is that cpufreq has "chose
predefined closest to a given frequency" functionality implemented in the
kernel while there is _no_ any reason to have this functionality implemented in
the kernel if we have sysfs interface exported by PowerOP in place - you just
_have_ to keep all possible functionality out of the kernel. CPufreq interface
is just subset of sysfs interface provided by PowerOP and _must_ be implemented
in userspace on top of sysfs interface - this is the proper way to scape
duplication. Such issue with cpufreq<->kernel userspace interface is consequence
of the fact that cpufreq implements incorrect design of PM stack layers and
interfaces. PowerOP solves this issues as well.
>
>> - The PowerOP interface was discussed in detail on this list and we
>> haven't heard any negative comments.
>
> Eh? Was I on different list?vb dfgdfv
>
>> - We are not advocating the integration with sleep states. We want to
>> get the PowerOP interface accepted and then we can build on it.
>
> Good.
>
>> 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?
>
> Well, you'll only get good interface review when you have
> Documentation/ , and it needs to go to lkml before it goes to any
> queues.
PM stack is too complex and heavy part to go in such pieces thru lkml. i expect
all linux pm experts to be on this list

Eugeny
> Pavel
>