Bug 482964

Created attachment 166785 [details]
Extract from a pkcon update to KDE Neon 6.0

PROBLEM: It is my practice to suspend the PC overnight rather than shutdown and restart.  Recently the Plasma session has not resumed properly from the suspend state.
SUMMARY:
Following a recent update, KDE neon 6.0 does not recover properly from a suspend state.  The problem occurred first after updating on Mar 3, affecting several KDE packages (extract from pkcon log is attached)
After this update, resuming an X11 session from a suspend state results in a black screen, i.e. the session is not rendered, although the session is functionally present (see steps to reproduce, below).
The following error from /var/log/syslog seems to be relevant (this is the oldest)
Mar  4 09:16:09 Odin sddm-greeter-qt6[4609]: QRhiGles2: Context is lost.
Mar  4 09:16:14 Odin sddm-greeter-qt6[4609]: QRhiGles2: Context is lost.
STEPS TO REPRODUCE:
1. Enter suspend state from X11 session command line in a Konsole window:
[code]$ sudo systemctl suspend[/code]
Observed: System suspends as expected, with no signal to monitor, standby indication on motherboard.
2. Resume with momentary power switch activation
Observed: Signal to monitor is restored, screen is deep black.
3. Move mouse
Observed: mouse cursor, which changes according to the UI elements not being displayed: the edges of the Konsole window are "visible" to the mouse cursor, and are displayed on the monitor as changed mouse cursor appearance.
4. Open a new shell on tty3 [Alt-Ctl-F3] and log in
Observed: new session is successfully started.
5. [code]$top[/code]
Observed: plasmashell is running, as are the backends of the desktop widgets.
6. Switch back to the X11 session on tty2 [Alt-Ctl-F2]
Observed: black screen as at steps 2-3.
7. Switch again to tty3, examine /var/log/syslog
$ grep -E "^Mar  9 10:1.*Gles2" /var/log/syslog
Mar  9 10:10:19 Odin plasmashell[3285]: QRhiGles2: Context is lost.
Mar  9 10:15:53 Odin plasmashell[3285]: QRhiGles2: Context is lost.
Mar  9 10:18:06 Odin plasmashell[3285]: QRhiGles2: Context is lost.
Observed: every time the X11 session is asked to write to tty2, the QRhiGles2 message is issued.
Also Observed: comments at https://codebrowser.dev/qt6/qtbase/src/gui/rhi/qrhigles2.cpp.html are incomprehensible to ordinary humans :)
8. From tty3, restart the sddm greeter
$ sudo service sddm restart
Observed: an X11 session, properly rendered on the screen is started, but on tty1.  tty2 session is ended.
Also observed: the same effect can be achieved by issuing the restart command "blind" in the non-displaying X11 session Konsole on tty2: it's there, and functional, just not displaying anything.
Info Centre report:
Operating System: KDE neon 6.0
KDE Plasma Version: 6.0.0
KDE Frameworks Version: 6.0.0
Qt Version: 6.6.2
Kernel Version: 6.5.0-25-generic (64-bit)
Graphics Platform: X11
Processors: 6 × AMD Phenom(tm) II X6 1090T Processor
Memory: 15.6 GiB of RAM
Graphics Processor: NVIDIA GeForce GTX 1080/PCIe/SSE2