Additional testing results After further investigation and testing with several Ubuntu Mainline kernels, I can confirm the behavior described in this report.
Hardware: GPU: AMD Radeon R9 380 (Tonga) Connection: HDMI Distribution: Zorin OS 18 (Ubuntu 24.04 based) Kernels tested: 6.14 6.13.2 6.13 6.12.74 6.11 6.10 6.9 Testing methodology: Multiple suspend/resume cycles were performed on each kernel using both X11 and Wayland sessions. Kernel parameters were restored to their default configuration to avoid influencing the results. Results: Under X11: After resume from suspend the HDMI display does not recover. The screen remains black with no signal and keyboard input becomes unresponsive. Under Wayland: Suspend/resume works normally. The display reliably returns after wake. Relevant kernel log messages include: *ERROR* No EDID read dce110_link_encoder_construct: Failed to get encoder_cap_info from VBIOS These messages appear during the AMDGPU initialization sequence. Conclusion: The issue appears consistently across kernels 6.9 through 6.14 when using X11. Wayland does not exhibit the problem and works as a reliable workaround. Disabling Display Core (amdgpu.dc=0) also restores functionality, but this is not a long-term solution since the non-DC path is deprecated. Given the consistent results across multiple kernels and configurations, the problem may be related to the interaction between the AMDGPU Display Core stack and X11 during suspend/resume. I remain available to perform additional testing within my capabilities if needed. -- 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
