https://bugs.kde.org/show_bug.cgi?id=516710
Bug ID: 516710
Summary: Greeter shows black screen after Thunderbolt 3 dock
power cycle (stale DRM connectors)
Classification: Plasma
Product: plasma-login-manager
Version First 6.6.0
Reported In:
Platform: CachyOS
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected]
Target Milestone: ---
SUMMARY
After power-cycling a Thunderbolt 3 dock while plasma-login-manager's greeter
is active
(or about to become active), the greeter renders a black screen. The greeter
process is
running but nothing is displayed. Killing the greeter session does not help —
the screen
stays black and a full reboot is required to recover.
This appears to happen because the DRM connector names change after the dock is
re-enumerated (e.g. DP-5 becomes DP-8), but the greeter continues rendering to
the
old (now-dead) connector.
STEPS TO REPRODUCE
1. Have a multi-monitor setup with external monitors connected via a
Thunderbolt 3 dock
2. System suspends or monitors turn off via DPMS
3. Monitors fail to wake (known TB3 dock firmware issue with Alpine Ridge
controllers)
4. Power-cycle the TB3 dock to force monitor re-connection
5. plasma-login-manager greeter appears — but screen is completely black
EXPECTED BEHAVIOR
The greeter should detect the connector change and re-render on the new active
connectors.
ACTUAL BEHAVIOR
The greeter shows a black screen. The plasmalogin-helper process is running but
no UI
is visible on any monitor. Killing the session or the greeter process does not
resolve
the issue — a full reboot is required.
ADDITIONAL NOTES
- This issue occurs regardless of the Wayland compositor (Hyprland or KDE
Plasma)
- The issue started when switching from SDDM to plasma-login-manager
- The laptop's built-in display (eDP-1) also shows nothing when this happens
- The dock monitors work fine after the reboot with the same physical setup,
confirming it's not a hardware issue
SYSTEM INFORMATION
- OS: CachyOS (Arch-based), rolling
- Kernel: 6.19.3-2-cachyos (x86_64)
- Hardware: Lenovo ThinkPad L14 Gen 2
- GPU: Intel Iris Xe Graphics (TigerLake-LP GT2)
- TB3 Dock: Lenovo ThinkPad Thunderbolt 3 Dock (Alpine Ridge JHL6540)
- Monitors:
- eDP-1: BOE 0x08C7 — 1920x1080@60Hz (built-in)
- DP-5: LG Electronics LG FHD — 1920x1080@100Hz (via dock)
- DP-7: Synaptics Inc Non — 1024x768@75Hz (via dock)
- plasma-login-manager: 6.6.0-2
- plasma-workspace: 6.6.0-1.1
- kscreenlocker: 6.6.0-1.1
- kwin: 6.6.0-1.1
- Qt: 6.10.2-1.1
- Hyprland: 0.53.3-2.1
- Session config (/etc/sddm.conf):
[Autologin]
Session=plasma
--
You are receiving this mail because:
You are watching all bug changes.
