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Re: Fan control on ibook2

> .../...

You are welcome to consolidate these into a single driver allowing
userland access to those values & finer thermal control :) A bit
like Colin Leroy did for the recent models ...

> I also have the feeling that my iBook operates at higher temperature
> if I using linux (esp. 2.6.4-vanilla or/and opengl-enabled xserver).
> A 'hotspot' is the frontmost left part of the bottom part of the iBook. 
> There are the hard disk _and_ the GPU. Perhaps the GPU works in a more power 
> consuming mode.

The ATI chip definitely has some advanced power management capabilities
that we don't know how to drive in Linux. Some of these are enabled by
the kernel (dynamic clock control) but disabled by XFree :( The reason
for that is some ASIC revs. have bugs related to those features, and
the XFree driver doesn't know which revs precisely, so it just disables
the feature completely. Could be worth putting that as an XF86Config
option ...

> Ah one interesting fact: 
> I believe I encountered that my iBook produced more heat at one point even it
> booted in OS_X. It was after an update of 10.2.n to 10.2.n+1. I think
> Quartz Extreme was introduced in this time frame. 
> Can someone cofirm this?

The use of the 3D engine definitely produce more heat.

> > 	Also. Temperature is always shown as uncalibrated in /proc/cpuinfo.
> > I've seen that this sentence is hard-coded. Is there a way to have it
> > calibrated ? 

The CPU internal TAU unit is mostly useless these days.

> The TAU ([?] thermal assist unit) functionality of some PowerPCs is  broken 
> or practically useless. But, you can find some descriptions how to calibrate 
> the CPU in the net. (PDF by IBM or Motorola)
> Frank
Benjamin Herrenschmidt <benh@kernel.crashing.org>

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