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

--- Comment #66 from Martin Peres martin.peres@ensi-bourges.fr --- (In reply to Alex Deucher from comment #64)

As far as percent vs. rpm, I'm not sure which would be preferred. I think the hwmon subsystem generally prefers rpm. Maybe add callbacks for both percent and rpm and then check rdev->pm.fan_pulses_per_revolution. If it's 0, expose it as a percent. if not, expose as rpm. Thoughts? Might be worth asking on the hwmon mailing lists.

No need to guess, everything is written here ;) https://www.kernel.org/doc/Documentation/hwmon/sysfs-interface

pwm1 should expose the duty cycle and nothing else. If you also have a tachometer, expose it with fan1_input :)

If you want to set the fan speed with RPM instead of the duty cycle, you'll need to use fan1_target. You may wonder what should happen if you set both pwm1 and fan1_target. Well, I would think that the latest you set should take precedence.

Please try to stick to the document I provided, for the sake of having a common behaviour. I hope I helped a little on this ;)