https://bugs.freedesktop.org/show_bug.cgi?id=73338

--- Comment #59 from Alex Deucher alexdeucher@gmail.com --- (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.