SUMMARY
KDE Wayland suspend fails completely on AMD TeraScale dual GPU hardware (HD 6520G + HD 6630M) resulting in graphics corruption or irrecoverable black screen. Same hardware works perfectly with KDE X11.

STEPS TO REPRODUCE
1. Use ASUS N53Ta laptop with AMD A6-3420M APU + dual GPU (HD 6520G integrated + HD 6630M discrete)
2. Boot openSUSE Tumbleweed with radeon driver (amdgpu blacklisted due to conflicts)
3. Login to KDE Plasma Wayland session
4. Execute suspend: systemctl suspend
5. Try to wake system with keyboard/mouse/power button

OBSERVED RESULT
- Default suspend (deep): Graphics corruption with horizontal lines and visual artifacts
- Alternative methods tested (s2idle, freeze): Complete black screen, system totally unresponsive
- No recovery possible via Ctrl+Alt+F1-F7, Alt+SysRq, or any other method
- Forced reboot required in all cases

EXPECTED RESULT
System should suspend and resume normally without graphics corruption, as it does when using KDE X11 session on the same hardware.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Tumbleweed 20250718
KDE Plasma Version: 6.4.3
KDE Frameworks Version: 6.16.0
Qt Version: 6.9.1
Kernel: 6.15.6-1-default (64-bit)
Graphics Platform: Wayland (issue occurs here, X11 works fine)

ADDITIONAL INFORMATION
Hardware Details:
- Manufacturer: ASUSTeK Computer Inc.
- Product: N53Ta (2011)
- CPU: 4 × AMD A6-3420M APU with Radeon HD Graphics
- Memory: 6 GiB RAM (5.3 GiB usable)
- GPU 1: AMD SUMO (HD 6520G - TeraScale integrated)
- GPU 2: AMD TURKS (HD 6630M - TeraScale discrete)

Driver Configuration:
- Using radeon driver only (amdgpu blacklisted to avoid conflicts)
- lsmod shows: radeon 2101248 45

Power State Information:
- /sys/power/state: freeze mem disk
- /sys/power/mem_sleep: s2idle [deep]
- GPU states: card0=D0 (active), card1=D3cold (suspended)

KWin Log Evidence:
kwin_wayland_drm: drmSetClientCap for Atomic Mode Setting failed. Using legacy mode on GPU "/dev/dri/card0"

Tests Performed:
- All suspend methods fail: systemctl suspend, s2idle mode, freeze mode
- Various kernel parameters tested (radeon.dmp, ACPI quirks): no effect
- systemd suspend hooks and kwin restart scripts: no effect
- Runtime power management configurations: no effect

Environment Comparison:
- KDE X11: Suspend works perfectly on same hardware
- GNOME Wayland: Previously worked on same hardware
- KDE Wayland: Complete failure with any suspend method

Related Hardware:
This issue appears specific to AMD TeraScale dual GPU configurations (2011-2012 era). Similar reports found:
- Ubuntu Bug #1313804 (HP Pavilion dv6 with same HD 6520G+6630M GPUs)
- KDE Bug #454639 (AMD flickering after Wayland suspend)
- Multiple openSUSE forum reports of KDE Wayland + AMD suspend issues

The hardware is pre-GCN (Graphics Core Next) and kwin_wayland appears to have compatibility issues with TeraScale architecture during suspend/resume operations.

Analysis conducted with assistance from Claude AI (Anthropic) including systematic testing and research of similar reported issues.