Re: [PATCH] acpi: move thermal trip handling to generic thermal layer

[Len Brown <lenb@kernel.org>]

On Fri, 16 Jan 2009, Thomas Renninger wrote:

> On Wednesday 17 December 2008 04:12:15 Matthew Garrett wrote:
> > On Wed, Dec 17, 2008 at 11:02:18AM +0800, Zhang Rui wrote:
> > > On Mon, 2008-12-08 at 20:59 +0800, Matthew Garrett wrote:
> > > > They're needed if you want to implement any sort of sensible
> > > > implementation of passive cooling. They might not be expressed in quite
> > > > the same way, but the basic concept is identical.
> > >
> > > Seeing tc1, tc2, tsp under /sys/class/thermal/ is not good because we
> > > don't want to make the generic thermal driver too ACPI specific, before
> > > we've really concluded some basic concepts for passive cooling.
> > > so why not do this after we have another generic thermal user with
> > > passive cooling support?
> >
> > They're not exposed in /sys/class, and I don't think doing so is a
> > sensible thing to do. If you know values for the hardware in question
> > then they should be supplied by the firmware. But even so, the generic
> > thermal layer needs a way of implementing passive cooling. Doing so
> > involves deriving a formula to describe the behaviour of the system
> > around the passive trip level, and the best used implementation of that
> > in Linux at the moment is the one described in the ACPI spec. I don't
> > see any real need to generate new terms to describe well documented
> > concepts, even if other implementations don't use ACPI.
> 
> If others need a specific algorithm, another (set of) callback function(s)
> could be added later which would provide the possibility of
> a platform specific override?

yeah, that is probalby the way to do it.
But until we have a 2nd customer besides ACPI,
we are kidding outselves if we think we can dream up a real "generic"
that will not need later modification...

--
Len Brown, Intel Open Source Technology Center