PWM GPIO on Raspberry Pi 3

[Benny Siegert <bsiegert%gmail.com@localhost>]

Hi!

I added a 5V PWM fan to my RPi 3 running 10.1 in 32 bit mode, as 
earmv7hf. I connected the PWM control pin to GPIO18, as per the article 
in 
https://blog.driftking.tw/en/2019/11/Using-Raspberry-Pi-to-Control-a-PWM-Fan-and-Monitor-its-Speed/.

The thing is, I can only switch the fan on and off from there. I'd like 
to use the actual PWM facility to run it at lower speeds.

How is PWM GPIO supposed to work? I found a thread from 2019 that 
suggests that the hardware PWM on the RPi3 would need driver support 
that we do not have.

For software PWM, I tried this command that I found in the manpage:

gpioctl gpio0 attach gpiopwm 18 1

which results in "invalid argument".

I think the gpiopwm driver is not loaded, but there doesn't seem to be a 
module for it either.

Any hints?

--
Benny