Re: [PATCH 4/6] thermal: add sanity check for the passive attribute

From: Zhang Rui
Date: Mon Aug 31 2009 - 04:36:00 EST

On Thu, 2009-08-27 at 00:48 +0800, Frans Pop wrote:
> On Wednesday 26 August 2009, Matthew Garrett wrote:
> > On Wed, Aug 26, 2009 at 06:17:23PM +0200, Frans Pop wrote:
> > > Values below 40000 milli-celsius (limit is somewhat arbitrary)
> > > don't make sense and can cause the system to go into a thermal
> > > heart attack: the actual temperature will always be lower and
> > > thus the system will be throttled down to its lowest setting.
> >
> > Not keen on this - it's a pretty arbitrary cutoff, and there are some
> > cases where someone might want this value. Policy belongs in userspace,
> > and all that.
> What cases do you see? Testing? Or systems that might have to operate at
> such a low temperature? I deliberately chose a value that's at a level
> that's easy to reach.
> I agree it is arbitrary, but it will prevent major confusion when someone
> like me echo's 95 directly in sysfs.

this is a problem.
how about something like:

printk(KERN_WARNING PREFIX "Passive trip point too low, this may"
"slow down your laptop because processors are throttled "
"whenever the temperature is higher than %dC\n", state/1000);


> Would 1000 (1 ÂC) perhaps be more acceptable as a limit? I doubt there are
> valid use-cases for below 0 temps :-)

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