amdgpu: failure to resume, black screen
Brief summary of the problem:
When the display is attached to an normal power outlet, suspend/resume works just fine.
When using a master/slave power socket, with the computer as master and the display as slave (which means the slave power is cut when the power drawn from the master goes below X watts), the display fails to resume.
When the problem occurs, the display keeps telling "lost signal". A remote lightdm restart works sometimes, but not always. A blind Ctrl+F1 and manual display power cycle also works sometimes, but not always. In any case, there're no related warnings or errors in dmesg AFAICT.
Hardware description:
- CPU: Xeon E3-1231 v3
- GPU: Radeon R9 380X, "Tonga"
- System Memory: 32GB
- Display(s): LG 32UD59-B
- Type of Display Connection: DP
System information:
- Distro name and Version: Debian sid
- Kernel version: 6.5, but problem exists for a long time
- Custom kernel: n/a
- AMD official driver version: n/a, upstream driver