Created attachment 186188 [details] This is the full output of running journalctl SUMMARY KWin/Wayland 6.5.0: DisplayPort monitor freezes on HDMI or Thunderbolt hot-plug, amdgpu "Mode Validation Warning" in logs STEPS TO REPRODUCE 1. Start a Plasma (Wayland) session on a computer with an AMD Ryzen 5 7430u (Renoir graphics). 2. Use a single monitor connected via DisplayPort (e.g., 3440x1440 @ 120Hz). 3. Once the desktop is active, hot-plug a second monitor into the HDMI port. OBSERVED RESULT Here is a complete bug report, pre-filled with all the information we've gathered. You can copy and paste this directly into the KDE bug tracker. SUMMARY KWin/Wayland 6.5.0: DisplayPort monitor freezes on HDMI or Thunderbolt hot-plug, amdgpu "Mode Validation Warning" in logs STEPS TO REPRODUCE Start a Plasma (Wayland) session on a computer with an AMD Ryzen 5 7430u (Renoir graphics). Use a single monitor connected via DisplayPort (e.g., 3440x1440 @ 120Hz). Once the desktop is active, hot-plug a second monitor into the HDMI port or with a Thunderbolt cable. OBSERVED RESULT The primary DisplayPort monitor freezes after a moment. The image is static and does not update. The newly connected HDMI monitor does not receive a signal (remains black). The system itself does not crash (e.g., the mouse cursor can still move, but its image is not updated on the frozen screen). Unplugging the HMDI or thunderbolt cable returns everything to normal on the DisplayPort connection. The kernel log (journalctl -k -b -1 | grep -iE "(amdgpu|drm|kwin|error|failed)") shows the following error spammed at the moment of the hot-plug: amdgpu 0000:05:00.0: [drm] Mode Validation Warning: Total vertical active bandwidth failed validation. EXPECTED RESULT Both monitors should become active. The Plasma desktop should extend or mirror to the newly connected HDMI or Thunderbolt monitor, and the primary DisplayPort monitor should remain responsive. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Arch Linux running 6.17.5.arch1-1 KDE Plasma Version: 6.5.0 KDE Frameworks Version: 6.19.0 Qt Version: 6.10.0 ADDITIONAL INFORMATION 1. This is a Wayland-Specific issue: This bug ONLY occurs in the Plasma (Wayland) session. The exact same hot-plug procedure in a Plasma (X11) session works perfectly every time. 2. As far as I can tell, this is not a new kernel issue: This bug was tested and confirmed on two different kernels: linux (mainline): 6.17.5-arch1-1 linux-lts (Long-Term Support) The behavior is identical on both kernels. 3. Hardware: Machine: Blackview MP100 mini pc CPU/APU: AMD Ryzen 5 7430u with Radeon Graphics (Renoir) 4. KWin Support Information: Version ======= KWin version: 6.5.0 Qt Version: 6.10.0 Qt compile version: 6.10.0 XCB compile version: 1.17.0 Operation Mode: Wayland Output backend ============== Name: DRM Atomic Mode Setting on GPU 0: true Screens ======= Number of Screens: 1 Screen 0: --------- Name: DP-1 Enabled: 1 Geometry: 0,0,3440x1440 Physical size: 797x334mm Scale: 1 Refresh Rate: 120000 Adaptive Sync: never Compositing =========== Compositing is active Compositing Type: OpenGL OpenGL vendor string: AMD OpenGL renderer string: AMD Radeon Graphics (radeonsi, renoir, ACO, DRM 3.64, 6.17.5-arch1-1) OpenGL version string: 4.6 (Core Profile) Mesa 25.2.5-arch1.2 OpenGL platform interface: EGL OpenGL shading language version string: 4.60 Driver: Unknown GPU class: Unknown OpenGL version: 4.6 GLSL version: 4.60 Mesa version: 25.2.5 X server version: 1.24.1 Linux kernel version: 6.17.5 Direct rendering: Requires strict binding: no Virtual Machine: no OpenGL 2 Shaders are used