Power Mode and Fan Control

Problem

No fan and power mode control is available in Linux.

Solution

There is a ec-su_axb35-linux kernel module written by Christoph Metz.

It allows you to:

• read current fan speeds and modes
• switch modes of each of the three available fans
• control fan speed in fixed mode
• control fan speed with custom curves in curve mode
• read current power mode
• change current power mode
• read current APU temperature

Generic Installation

1. Install module building dependencies (depends on your distro, on debian/ubuntu install build-essential and linux-headers-$(uname -r) packages).
2. Clone the repo with git clone https://github.com/cmetz/ec-su_axb35-linux.git.
3. Build and install the module with cd ec-su_axb35-linux && sudo make install.
4. Try loading the module with modprobe ec_su_axb35 and check your dmesg afterwards. You should see the Sixunited AXB35-02 EC driver loaded message.
5. Run scripts/info.sh and check that all information is there.
6. Run scripts/test_fan_mode_fixed.sh, it should test your fans on all 6 fixed levels.
7. If everything is good, you can make the module automatically load on system boot with sudo echo ec_su_axb35 >> /etc/modules. If it says "permission denied", drop into root console with su or sudo su - and try again.

Usage

Reading and writing all of the parameters happens through sysfs with /sys/class/ec_su_axb35 path. You can find detailed information in the repo's readme file.

Some examples:

• cat /sys/class/ec_su_axb35/fan2/rpm to get current rpm of fan2
• echo fixed > /sys/class/ec_su_axb35/fan3/mode && echo 2 > /sys/class/ec_su_axb35/fan3/level to switch fan3 to fixed mode and set speed to level 2
• echo balanced > /sys/class/ec_su_axb35/apu/power_mode to set power mode to balanced (85W)

You can also call su_axb35_monitor anywhere to monitor all available values in realtime:

To apply specific settings at system startup, place them in your rc.local file or utilize any other methods for executing commands during boot, such as creating a systemd unit. In the future, these parameters will also be configurable through module options.

Custom Curves

The custom curves define temperature thresholds for fan power levels:

• Ramp-up curve (/sys/class/ec_su_axb35/fanX/rampup_curve): temperature points where fan increases to the next level
• Ramp-down curve (/sys/class/ec_su_axb35/fanX/rampdown_curve): temperature points where fan decreases to the previous level

For example, with these settings:

• rampup_curve = 60,70,83,95,97
• rampdown_curve = 40,50,80,94,96

When CPU is heating up:

• Below 60°: Fan at level 0 (minimum)
• At 60°: Increases to level 1
• At 70°: Increases to level 2
• At 83°: Increases to level 3
• At 95°: Increases to level 4
• At 97°: Increases to level 5 (maximum)

When CPU is cooling down:

• Above 96°: Fan stays at level 5
• Below 96°: Decreases to level 4
• Below 94°: Decreases to level 3
• Below 80°: Decreases to level 2
• Below 50°: Decreases to level 1
• Below 40°: Decreases to level 0

This creates a buffer at each level that prevents the fan from rapidly switching between speeds when temperature fluctuates around threshold values.

Curves are being applied only when curve mode is set on a specific fan, each fan has their own curves.

Fine-tuning Power Limits

If you want more gradual control over power modes, there's a RyzenAdj utility.

Main 3 parameters we are interested in are:

• STAPM LIMIT (sustained power draw)
• PPT LIMIT FAST (boost power draw)
• PPT LIMIT SLOW (average power draw)

Default values on all 3 selectable power modes (use ryzenadj --info to read them):

Example on setting the power limit to static 100W with no boost:
ryzenadj --stapm-limit=100000 --fast-limit=100000 --slow-limit=100000

Note that changing the power mode via the EC controller (using ec-su_axb35-linux or otherwise) resets these values to their defaults.

Relevant Pages

• Guides/Hardware-Monitoring
• Guides/Power-Modes-and-Performance