How to Enable and Test the New AMDGPU Power Module in Linux 7.2

Introduction

With the upcoming Linux kernel 7.2, a new AMDGPU DC power module is set to be introduced, aiming to align Radeon power management behavior more closely with that of Microsoft Windows. This module, queued for DRM-Next and expected to merge in June, brings significant improvements for AMD GPU users. This step-by-step guide will help developers and advanced users understand, enable, and test this power module on their systems.

How to Enable and Test the New AMDGPU Power Module in Linux 7.2

What You Need

Hardware: A system with an AMD Radeon GPU (GCN or newer architecture recommended)
Operating System: A Linux distribution (preferably with GCC, make, and git installed)
Kernel Source: Linux kernel source code (version 7.2-rc1 or later, or a DRM-Next branch)
Build Tools: GCC, make, flex, bison, libelf-dev, openssl-dev
Firmware: Latest AMDGPU firmware package (available from linux-firmware)
Basic Knowledge: Familiarity with kernel compilation and command-line operations

Step-by-Step Guide

Step 1: Understand the Power Module

The AMDGPU DC power module is a new addition to the kernel's Direct Current (DC) power management subsystem. Its primary goal is to replicate the power-saving and performance-tuning behaviors found in the official Radeon drivers on Windows. This includes dynamic voltage and frequency scaling (DVFS), better idle power management, and seamless switching between performance states.

Step 2: Obtain the Kernel Source

You need a kernel tree that contains the new power module. The easiest way is to clone the Linux kernel repository and check out the appropriate branch. Use the following commands:

git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
cd linux
git checkout v7.2-rc1  # or a later release candidate

Alternatively, if you want the latest DRM-Next patches, you can pull from the drm-next branch of the DRM tree.

Step 3: Configure the Kernel

Enable the AMDGPU driver and the DC power module in the kernel configuration. Run:

make menuconfig

Navigate to Device Drivers → Graphics support → AMD GPU → DC (Display Core) support. Ensure the following options are enabled (set to y or m):

CONFIG_DRM_AMDGPU
CONFIG_DRM_AMDGPU_DC
CONFIG_DRM_AMDGPU_DC_POWER_MODULE (this is the new power module)

Save and exit. If you prefer to use a default config, you may need to manually set these options.

Step 4: Build the Kernel

Compile the kernel and modules with:

make -j$(nproc)
make modules_install
make install

This may take a while depending on your system. Ensure there are no errors. If you cross-compile or use a custom install path, adjust the commands accordingly.

Step 5: Update Firmware

The AMDGPU power module relies on latest firmware. Download and install the firmware package:

git clone https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
cd linux-firmware
make install

Alternatively, copy the amdgpu/ folder to /lib/firmware/amdgpu/.

Step 6: Update Bootloader

Ensure your bootloader (GRUB, systemd-boot, etc.) points to the new kernel. For GRUB, run:

sudo update-grub

Then reboot into the newly compiled kernel.

Step 7: Verify the Power Module is Active

After booting into the new kernel, check that the power module is loaded:

dmesg | grep -i power

Look for lines containing "DC power module" or "amdgpu: power module initialized". Also confirm that the module is built-in or loaded with lsmod | grep amdgpu.

Step 8: Test Power Management Behavior

Use tools to stress-test the new power management. Install stress or glmark2 for GPU load, and monitor power consumption with powertop or turbostat. Compare the results with older kernels or with Windows on the same hardware. Note any changes in thermal behavior or frequency scaling.

Step 9: Troubleshoot Common Issues

If the power module does not activate, check the following:

Ensure CONFIG_DRM_AMDGPU_DC_POWER_MODULE is enabled in your config.
Verify that the latest firmware is installed (missing firmware can cause fallback to legacy paths).
Check kernel logs for errors: dmesg | grep -i amdgpu.
If using an older GPU (pre-GCN), the module may not be fully supported.

Tips and Best Practices

Backup your current kernel: Always keep a working kernel entry in your bootloader before testing new builds.
Monitor power draw: Use hardware monitors like amdgpu-pm or sensors to verify the module's effect. You can install sensors from lm-sensors and check GPU power via sensors amdgpu-pci-*.
Keep up with DRM-Next: Since this module is queued for DRM-Next, you may want to follow the mailing list for updates: amd-gfx mailing list.
Contribute feedback: If you encounter issues, report them with detailed logs to the AMD GPU developers. Use the amdgpu driver bug tracker.
Use a dedicated test system: Avoid testing bleeding-edge kernel features on production machines unless you have fallback options.
Compare with Windows: For a true comparison, dual-boot the same system with Windows and run identical workloads, measuring performance per watt metrics.

By following this guide, you can experience the improved power management alignment offered by the new AMDGPU DC power module in Linux 7.2. This brings Linux closer to Windows-level Radeon optimization, benefiting both desktop and mobile AMD GPU users.

Tags: