Additional diagnostic results and final update. After further controlled testing I was able to narrow down the root cause of the suspend/resume issue affecting HDMI output.
Hardware AMD Radeon R9 380 (Tonga) Distribution Zorin OS 18 (Ubuntu 24.04 base) Display connection HDMI Desktop environments tested GNOME (X11 and Wayland) Kernels tested 6.8.0-101-generic (Ubuntu default) 6.12.0 6.12.74-061274-generic 6.13.0-061300-generic 6.13.2-061302-generic 6.14.0-061400-generic Observed behavior (without workaround) After suspend → resume the system frequently returns with no video signal when using an HDMI-connected monitor in X11 sessions. The monitor reports “no signal” and the system appears frozen from the user perspective. Relevant kernel messages observed include: [drm] *ERROR* No EDID read amdgpu: PCI CONFIG reset Wayland sessions usually recover the display correctly, but X11 sessions remain stuck with no video output. Diagnostic steps performed • Verified HDMI connector state via /sys/class/drm (connector reported as connected) • Verified EDID is correctly read at boot using xrandr --verbose • Reproduced the suspend/resume failure multiple times across all kernels listed above in X11 sessions Workaround / key finding Adding the kernel parameter amdgpu.dc=0 fully resolves the issue. With Display Core disabled: • suspend/resume works reliably • HDMI signal returns immediately • X11 sessions recover normally • Wayland sessions continue to function correctly Conclusion The issue appears to be related to Display Core handling of HDMI EDID reinitialization during resume on Tonga (R9 380). For now I will continue using the workaround. If needed I can provide additional logs or run further diagnostic tests. Many thanks to the maintainers and developers working on the amdgpu driver and the Linux graphics stack. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2142389 Title: amdgpu (R9 380) fails to resume from suspend (deep sleep) – black screen, requires hard reboot To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2142389/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
