I am using :-

[ Ubuntu 24.04 (Noble)](https://dl.armbian.com/rock-5b-plus/Noble_vendor_server)

from :-

[Radxa Rock 5B Plus - Armbian](https://www.armbian.com/rock-5b-plus/) 

Trying to turn fan on on Radxa Rock 5B+

 

selecting the device using armbian-config actually makes it disappear

 

Quote

> cat usr/local/bin/test_fan_run.sh
#!/bin/bash echo "Trun on Fan"
echo 0 > /sys/devices/platform/fd8b0010.pwm/pwm/pwmchip0/export
echo 10000 > /sys/devices/platform/fd8b0010.pwm/pwm/pwmchip0/pwm0/period
echo 5000 > /sys/devices/platform/fd8b0010.pwm/pwm/pwmchip0/pwm0/duty_cycle
echo normal > /sys/devices/platform/fd8b0010.pwm/pwm/pwmchip0/pwm0/polarity
echo 1 > /sys/devices/platform/fd8b0010.pwm/pwm/pwmchip0/pwm0/enable

 

I am getting `line 3: echo: write error:Device or resource busy`

Edited September 26, 20251 yr by AaronNGray

I use the desktop version and have the same issue.

2 hours ago, e.j. Frölich said:

I use the desktop version

HW (features are determined by kernel used in the image) related issues are shared among all variants, desktop, cli, minimal, Debian or Ubuntu. 

I have the default radxa image rock-5b-plus_bookworm_kde_b2 image with the fan working :-

https://github.com/radxa-build/rock-5b-plus/releases/download/rsdk-b2/rock-5b-plus_bookworm_kde_b2.output.img.xz

 

I/We need to try and find how this was built and the Linux DTD file the `uname -a` kernel reports as "Linux rock-5b-plus 6.1.84-1-rk2410" kernel.

 

rsetup :-

https://docs.radxa.com/en/rock5/rock5b/getting-started/interface-usage/fan

https://github.com/radxa-pkg/rsetup

 

 

 

 

Edited October 7, 20251 yr by AaronNGray

From the Circuit Schematic it looks like the Radxa Rock 5B+ RK3588 GPIO0-C0 is the fan I/O, GPIO pin 24, if thats correct.

 

I will verify I can access this on the Armbian distro.

 

Yeah fan working on :- 

https://github.com/radxa-build/rock-5b-plus/releases/download/rsdk-b2/rock-5b-plus_bookworm_kde_b2.output.img.xz

 

@Igor - Can you have a look at this please.

 

I have retrieved the devicetree's for the radxa Debian release on which the fan works and my Armbian Ubuntu build using

 

dtc -I fs /sys/firmware/devicetree/base

uname -a

lsb_release -a

 

https://github.com/AaronNGray/radxa-rock-5b-plus

 

The 'pwm-fan' nodes are the same.

 

Edited October 24, 2025Oct 24 by AaronNGray

There is a minor difference in another node: "phandle = <0x2c2>;" in radxa.dts and phandle = <0x2c3>;

No clue if that's the culprit or if there is  something on software-side to make fan work.

51 minutes ago, Werner said:

No clue if that's the culprit

A phandle is a magical number assigned during DTB assembly, whose value is irrelevant as long as it references the same node with the phandle property.
The magic value can change when the structure changes because it is assigned arbitrarily; for example, by inserting an additional node.

this is my [fix plan](https://github.com/icecreamzhao/rock5b-plus-fan-fix)