Bug#984564: Still exists in 5.10.0-4-amd64 #1 SMP Debian 5.10.19-1

[Georg Borgström <geobo@lysator.liu.se>]

Dear Maintainer,

The same behaviour exists in 5.10.0-4-amd64 #1 SMP Debian 5.10.19-1.

I can reproduce the error by switching off the monitor. When I power it on,
the error always comes. The only time the error appears is when the monitor
has been powered off and is powered on again. At least as far as I can tell.

It's always six lines of "gdk_monitor_get_scale_factor: assertion
'GDK_IS_MONITOR (monitor)' failed" followed by one single line with
"[drm] *ERROR* CPU pipe A FIFO underrun"

Best regards
Georg