AMDGPU Driver Reverts Problematic Commit After Widespread Linux 6.19 Regressions

The AMDGPU driver maintainers have been forced to revert a problematic commit in the Linux 6.19 development kernel after it introduced a series of regressions impacting a wide range of AMD Radeon hardware. The change, which was introduced during the 6.19 merge window to optimize display manager behavior during idle periods, had unintended consequences that manifested across multiple subsystems and user reports.

The Problematic Commit

The reverted code altered how the AMDGPU driver handles workload settings in the display manager during idle optimization. While the intent was to improve power efficiency, the implementation caused unexpected fallout. The revert commit, merged as part of this week's DRM kernel graphics driver fixes, notes it addresses a variety of bug reports that users have been filing against the Linux 6.19 development kernel.

Impact on AMD Radeon Users

The scope of the regression was significant, affecting both functionality and performance:

• HDMI Audio Issues: Users reported missing start of streams and speakers producing an audible "click" when the system went idle
• GPU Instability: The AMD Radeon RX 7900 XTX was particularly affected, with reports of the GPU falling off the bus entirely on newer kernels
• Performance Regression: The 7900 XTX showed measurable performance degradation
• Audio Dropouts: GPU clock changes were causing HDMI audio dropouts during normal operation
• Video Stuttering: Users running other GUI programs in parallel with the RX 7600 experienced stuttering video playback

These issues were reported across the upstream bug tracking systems, indicating the problem affected a substantial portion of the AMD Radeon user base on the bleeding edge of kernel development.

Timing and Resolution

The good news is that this problematic commit was identified and reverted in time for the upcoming Linux 6.19 stable release, scheduled for February. The revert was merged on Friday as part of the weekly DRM kernel graphics driver fixes pull request. This means the stable 6.19 release should not contain the regression, sparing most users from experiencing these issues.

The changes are already in place for tomorrow's Linux 6.19-rc7 kernel release, which is the final release candidate before the stable version. Users testing the development kernel can update to rc7 to get the fix.

Broader DRM Fixes

Beyond the AMDGPU revert, this week's DRM fixes pull request also includes other AMDGPU driver fixes, Intel Xe driver fixes, and various last-minute work for other graphics drivers. This is typical for the final stages of a kernel development cycle, where maintainers address any remaining issues before the stable release.

Context for Homelab Builders and Enthusiasts

For those running AMD Radeon hardware in homelab setups or as primary graphics cards, this episode highlights the importance of kernel version selection. While the 6.19 stable release will be safe, users running development kernels should be aware that regressions like this can occur. The AMDGPU driver is actively developed, and while it generally provides excellent performance, the rapid development pace means occasional issues slip through.

The revert also demonstrates the effectiveness of the Linux kernel's regression reporting and fix process. User reports were acted upon quickly, and the fix was integrated before the stable release. For homelab builders who measure everything, this is a good reminder to monitor kernel changelogs and consider testing new versions on non-critical systems first.

Looking Ahead

With the revert in place, AMD Radeon users can expect the Linux 6.19 stable release to deliver the intended improvements without the problematic side effects. The display manager idle optimization feature may be revisited in a future kernel version with a more refined implementation that avoids these regressions.

For now, the immediate takeaway is that the Linux 6.19-rc7 release candidate and the upcoming stable version will be safe for AMD Radeon users, with the HDMI audio, GPU stability, and performance issues resolved.

AMD Radeon graphics cards, including the affected RX 7900 XTX and RX 7600 models.