Linux 7.0 Kernel Delivers Critical AMDGPU Fixes for Legacy Radeon Hardware

The upcoming Linux 7.0 kernel merge window has incorporated substantial AMDGPU driver enhancements targeting persistent compatibility issues with older Radeon graphics cards. Following February's initial Direct Rendering Manager updates, this latest pull request focuses exclusively on stability improvements for aging AMD hardware, addressing long-standing problems affecting analog displays and Apple MacBooks.

Radeon GPU analog connectors (like those on HD 7790) now have improved stability under AMDGPU DC display code

Engineer Timur Kristóf from Valve's open-source Linux graphics team spearheaded the core fixes, continuing his work to refine support for Graphics Core Next (GCN) 1.0 and 1.1 architectures. These GPUs transitioned from the legacy radeon driver to the modern AMDGPU driver by default starting with Linux 6.7, but lingering issues remained:

1. Analog Connector Black Screen Fix: Radeon HD 7790 (GCN 1.1) and similar cards experienced intermittent black screens when driving displays through VGA or DVI-I analog connectors. This occurred specifically when using the AMDGPU Display Core (DC) infrastructure. The patch resolves timing synchronization between the GPU's display controller and analog signal generation circuits, eliminating screen blanking during boot and desktop operation. Testing confirms consistent signal output matching legacy driver behavior.

2. Apple MacBook Pro Flicker Resolution: Systems like Intel-based MacBook Pros with Radeon Pro 560 (Polaris/GCN 4) dGPUs exhibited cursor corruption and desktop flickering under GNOME on Wayland. Alex Deucher's patch modifies virtual address space allocation for the discrete GPU when VGA memory regions are active, preventing memory mapping conflicts between integrated and discrete graphics. This eliminates visual artifacts during cursor movement and window compositing.

Additional fixes include:

• Hainan GPU (GCN 1.0) command streamer stability improvements
• Fastboot optimizations reducing display initialization latency
• Preparatory updates for upcoming AMD IP blocks

These changes are particularly valuable for homelab and legacy workstation environments where older Radeon cards remain in service for display outputs or compute tasks. While not performance-enhancing, the patches eliminate critical usability blockers. Power consumption remains consistent with prior measurements, though users may observe marginal reductions in GPU memory power states during idle desktop operation due to stabilized display signaling.

Build Recommendations:

• Users experiencing analog display issues on HD 7000-series cards should test Linux 7.0 release candidates
• MacBook Pro owners with Radeon dGPUs can validate the flicker fix via Linux 7.0 Git
• Most fixes will be backported to Linux 6.8/6.9 stable kernels within weeks

For technical details, review the DRM fixes merge and AMDGPU driver documentation. Valve's continued investment in legacy AMD support demonstrates the importance of backward compatibility in open-source graphics, ensuring decade-old hardware remains viable in modern Linux environments.