Fan control for PowerMac7_3 (#3)

[H. Peter Anvin]

Benjamin Herrenschmidt wrote:
> On Sat, 2004-10-16 at 15:32, H. Peter Anvin wrote:
> 
> 
>>It's the backside fan that oscillates; backside_fan_pwm varies between 
>>30 and 100 in what is pretty much a squarewave.  See attached graph (and 
>>note how the other fans vary with workload.)
>>
>>I probably need to write a "power virus" program for the G5 to really 
>>test out the high end (a power virus is a program which keeps the chip 
>>running as hard as it can; generally keep all pipelines stuffed.)
> 
> 
> Strange... The values used seem to be identical to OS X (a 75° target
> which is high actually, and a different G_d value than old U3). I would
> need to see the debug output and compare with the OS X driver built with
> debug output as well (don't ask me to fully understand the math of the
> PID algorithm)
> 

If you want the file I used to produce the graph, it has all the entries 
in /sys/devices/temperature snapshotted at 100 ms intervals (attached) 
in the following order:

[time] backside_fan_pwm backside_temperature cpu0_current
cpu0_exhaust_fan_rpm cpu0_intake_fan_rpm cpu0_temperature cpu0_voltage
cpu1_current cpu1_exhaust_fan_rpm cpu1_intake_fan_rpm cpu1_temperature
cpu1_voltage drives_fan_rpm drives_temperature

I've also attached /var/log/dmesg in case that's useful.

	-hpa
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