[BUG REPORT] AMD Radeon R9 380 (Tonga) – HDMI no signal after suspend (possible EDID regression since kernel 6.13)

[Danilo Machado]

Hello,

I am reporting a regression affecting my AMD Radeon R9 380 (Tonga / GCN 1.2) related to HDMI output after system suspend. I am sharing detailed observations in case they help identify the cause.

This issue has also been reported in the Ubuntu bug tracker:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2142389

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System information

GPU: AMD Radeon R9 380 (Tonga / GCN 1.2)
CPU: AMD Ryzen 5 5500
Motherboard: Gigabyte B450 AORUS PRO WIFI
Connection: HDMI directly to monitor
Distribution: Zorin OS 18 (Ubuntu-based)
Desktop environments tested: GNOME (Wayland and X11 sessions)

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Summary of the issue

Since kernel 6.13, my system occasionally resumes from suspend with no HDMI signal.
The system itself resumes normally, but the monitor remains black and reports no input signal.

This behavior appears related to a failure in EDID detection or HDMI link reinitialization after suspend.

Kernel 6.12 and earlier do not show this behavior.

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Kernel behavior comparison

Kernel 6.12.x
Stable operation
Suspend and resume work correctly
HDMI output always restored

Kernel 6.13.x and newer
Regression observed
After suspend, the system resumes but HDMI signal is sometimes not restored

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Relevant kernel log excerpt

During resume when the issue occurs, the following messages appear in dmesg:

[drm] ERROR HDMI-A-1: probed a monitor but no|invalid EDID
amdgpu 0000:0b:00.0: amdgpu: failed to read EDID from connector HDMI-A-1
amdgpu 0000:0b:00.0: amdgpu: link training failed during resume

These messages suggest that EDID detection or HDMI link reinitialization may be failing during the resume sequence.

The complete logs and additional system information are available in the Launchpad bug report linked above.

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Wayland vs X11 behavior

I also tested different display sessions to help isolate the issue.

Wayland session:
Suspend and resume work reliably in my tests. The monitor wakes normally and HDMI output is restored.

X11 session:
Short suspend cycles usually resume correctly. However, after longer suspend periods (approximately 10–15 minutes or more), the system resumes but the monitor receives no signal.

The system itself continues running normally in the background.

This suggests that the issue may involve display reinitialization during deeper power-state transitions or differences in display management between Wayland compositors and the X11 stack.

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Troubleshooting attempts

Before reporting this bug, I performed several tests and troubleshooting steps:

• Tested multiple kernel versions
• Confirmed stable behavior with kernel 6.12
• Reproduced the issue with newer kernels
• Tested both Wayland and X11 sessions
• Verified HDMI cable and monitor behavior
• Compared suspend durations to identify patterns
• Collected logs and monitored dmesg output

Because kernel 6.12 remains stable on this system, I have temporarily stayed on the LTS kernel (6.8 series) to maintain reliability.

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Background

I was previously a long-time Windows user (from Windows XP through Windows 11), but I recently migrated fully to Linux and do not plan to return to Windows.

My goal is to maintain a stable Linux system and eventually upgrade to newer kernels once this regression is fully resolved.

I appreciate the work of the kernel and AMDGPU developers and hope this report helps identify the issue.

If additional logs, kernel parameters, or test kernels would be helpful, I would be glad to assist with further testing.

Best regards,

Danilo Machado