Comment # 17 on bug 1213380 from Samuel Conway

(In reply to Samuel Conway from comment #16)
> (In reply to Takashi Iwai from comment #14)
> > So, now you could install the system with DP-DP?  And on the running system,
> > try to switch to DP-HDMI.  Do you see the same problem?  When you reconnect
> > back to DP-DP, does it recover again?
> > 
> > If all yes, please try like the following:
> > - Boot with DP-DP, go up to GUI desktop
> > - Enable the debugging of drm, run below as root
> >     echo 0x1e > /sys/module/drm/parameters/debug
> > - Re-connect to DP-HDMI, and you'll see a buggy screen
> > - Re-connect back to DP-DP, screen recovered
> > - Save the output "dmesg" command, and attach the output to Bugzilla
> 
> Did as as requested, had video output for both DP-DP and DP-HDMI. output of
> dmesg  is attached.

I powered off device and took to room with projector, first booting with DP-DP
monotor, successful video output, swapped to DP-HDMI for projector projector,
but again no video output, just black screen.

Rebooted again with DP-DP, still no output. Swapped again to DP-HDMI (still
nothing) so I created a new dmesg export: dmesg-20230803-1 and attached it.
Also swapped adapters since I have two, but no success.

let me know if I can test anything else.
regards