Subject: Re: iMac G5: experimental thermal & cpufreq support

From: Benjamin Herrenschmidt <[email-masked]>
Date: Fri, 30 Sep 2005 10:26:59 +1000

On Thu, 2005-09-29 at 16:28 -0700, Geoff Levand wrote:
> Benjamin Herrenschmidt wrote:
> > The algorithm itself is extracted from darwin. However, it's a rather
> > complex modified version of the PID algorithm, and thus it could use
> > some review to make sure I got everything right.
> > 
> 
> As we are already in the digital domain, I would think it would be 
> more savvy to use a digital controller than try to simulate an
> analog controller...  Why don't you abstract the control algorithm 
> such that you can plug in others as they are developed.

Because I don't know much about those control algorithms, and all the
calibration data provided by the firmware is in the form of factors for
these algorithms, I wouldn't know how to "unmangle" them to use with
different ones.

Actually, the control algorithms (PID and modified PID) are in a
"helper", so it's fairly easy for the platform module to use whatever it
wants, feel free to submit other algorithms :) But for Apple machines,
I'd rather use what I have calibration data for, unless you can produce
something that works without any...

Ben.