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Re: powerbook fan behaviour, therm_adt7467


> As long as you make sure there's some code to switch the fans to full
> speed at some threshold you should be safe. The module needs some more
> tweaking anyway - it's written for iBook where there's a CPU and GPU fan
> but the PowerBook seems to have just two exhaust fans, and the sensors
> don't sit on the CPU and GPU, exactly (the 'GPU' sensor really measures
> the power supply temp). For me, the 'GPU' limit needs to be reduced or
> both fans need to be synced to identical speed to keep the machine from
> crashing too often. Depending on your sensor and fan locations, you might
> benefit from similar tweaks (list the fan node in the OF device tree,
> mine's at uni-north/i2c/fan).

hmm, I'm a bit puzzled right now: according to the given location in the OF 
device tree, I have only one fan in my 12" powerbook, located at the "REAR 

anyways, if you have 2 exhaust fans, it would make sense to set the limit to 
min(cpu_limit, gpu_limit) for both of them... however, if I'm not mistaken, a 
temporary workaround for this would be to tamper with lines 46,47 in 
therm_adt746x.c and recompile the module (line 47 seeming to be the more 
relevant one).

> Making the fan start out slower and gradually increasing the speed would
> be just a minor add-on :-)

message received, I'll look into that... it would probably be nice to have 
another module parameter like "fan_step" and "limit_override", so that when 
the temperature reaches "limit", the fan speed is set to fan_speed and then 
gets increased by fan_step every one or two degrees until limit_override is 
reached which would in turn set the fan to full speed.

does anybody know how OS X handles the fan speed i.e. at which temperatures 
does it start the fan(s), what increments does it use and when does it go to 
full speed?

Georg Kaindl

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