cpufreq user<->kernel interface removal [was Re: community PM requirements/issues and PowerOP] (fwd)

[Pavel Machek]

(I typoed in lkml address, sorry, and please include correct address
in Cc).

----- Forwarded message from Pavel Machek <pavel@xxxxxx> -----

To: "Eugeny S. Mints" <eugeny.mints@xxxxxxxxx>, lkml@xxxxxxxxxx
Cc: Preece Scott-PREECE <scott.preece@xxxxxxxxxxxx>,
	Matthew Locke <matt@xxxxxxxxxxx>, Greg KH <greg@xxxxxxxxx>,
	Amit Kucheria <amit.kucheria@xxxxxxxxx>,
	pm list <linux-pm@xxxxxxxxxxxxxx>,
	Mark Gross <mgross@xxxxxxxxxxxxxxx>,
	Igor Stoppa <igor.stoppa@xxxxxxxxx>
Subject: cpufreq user<->kernel interface removal [was Re: community PM requirements/issues and PowerOP]
X-Warning: Reading this can be dangerous to your mental health.

Hi!

(cc-ed to lkml).

> >>Just as a data point, "keeping the cpufreq interface" is
> >>irrelevant to a number of us, because we configure it out
> >>of the system.  I'm not really arguing that we should get
> >>rid of an existing kernel interface, but I don't see any
> >>reason why we shouldn't be able to have a separately
> >>configurable interface if cpufreq doesn't meet our needs.
> >
> >Configurable interfaces are evil,
> Are you saying that not having sysfs attribute nodes for entities which 
> don't exist in a certain configuration is evil?

I'm saying that

#ifdef CONFIG_FOO
	provide user<->kernel interface
#endif

is evil.

> >patch. You have developed your own little interface that suits your
> >needs -- and that's fine -- but now you are trying to push it into
> >mainline... and that is not, because those interfaces were not really
> >designed to work together.

> once cpufreq userland interface functionality which does not belong to the 
> kernel is moved out of the kernel cpufreq interface becomes a subset of 
> PowerOP sysfs interface. In other words this means that improvements of PM 
>  stack layers/interfaces design will allow to design/develop an universal 
> userspace interface. We'd prefer to move gracefully in this direction 
> though.

<tongue-in-cheek warning>

Yes, once cpufreq userland interface is removed from kernel, merging
powerop is reasonable thing to do. But please get at least
Documentation/feature-removal-schedule.txt patch merged to mainline
before attempting next powerop submission :-P.

<I'm trying to explain that removing cpufreq userland interface is
about as probable as MS Linux, and only a bit less likely than hell
freezing over.>
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

----- End forwarded message -----

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