Comment # 59 on bug 73338 from Alex Deucher

(In reply to Chernovsky Oleg from comment #58)
> Can you elaborate on what each bit of this control register means? Maybe I
> just can't into abbreviations :)

TMIN - temp at which the fan would be turned on
FDO_PWM_MODE - which PWM mode to use:
0 - static PWM based on fuse value
1 - static PWM based on CG_FDO_CTRL0.FDO_STATIC_DUTY value
2 - dynamic PWM
5 - static PWM based on RPM CG_TACH_CTRL.TARGET_PERIOD value
TACH_PWM_RESP_RATE - amount to adjust PWM in tach mode

As far as I know, only values 1 and 5 are used for FDO_PWM_MODE in the driver
for manual control.  I'm not sure what dynamic PWM (2) means or how it works. 
It might be used by the smc for fan control.

I also noticed a minor error in the RPM control setup, and I've pushed a patch
to my 3.19-wip branch.