Bug 1221892

Turns out that I can log into Plasma 6 / X11 and immediately log out to re-enable the two disabled displays. Logging back in finds everything working normally.

This looks like a timing issue, i.e. driver is not fully initialized yet when desktop starts. In order to verify this theory you can start in runlevel 3, login to Linux console. Then run 'init 5'.

Thanks for your help. Perhaps I didn't understand your instruction but here's what I did:

* reboot the system

* the login screen appears (and the two displays connected to the second video card are not active)

* I press Ctrl+Alt+ F1 to get to a tty

* I type the command: sudo init 5

(Nothing happens? or perhaps I don't see what you are looking for?)

* I type Ctrl+Alt+F2 to go back to the graphical login

(No change that I can see.)

Sorry if I didn't understand what you were looking for? Please let me know what to try next.

By the way I can confirm that logging into Plasma and logging out does activate the two displays on the second graphics card.

Thanks again

A Better work-around. From a TTY I type:

$ sudo systemctl restart sddm

and all six displays are working :)

What I meant was telling grub to boot into runlevel 3, then switch to runlevel 5 with displayamanger acitve. 

Not so easy to explain. When the bootmanager grub starts, select the righ entry, then press 'e' for edit then add to the line with 'linuxefi ...' at the end a 3 (for runlevel 3). Then press F10 to boot this. The login into Linux console and
run 'init 5'.

With starting into runlevel 5, then restarting displaymanager via 

  sudo systemctl restart sddm

things are rather similar. Maybe not exactly.

(In reply to Stefan Dirsch from comment #5)
> What I meant was telling grub to boot into runlevel 3, then switch to
> runlevel 5 with displayamanger acitve. 
> 

Thanks again. I understand this time.

Yes, after booting into Run Level 3 I am able to sudo init 5 which brings me to the graphical login screen. Along the way I was able to see the graphical NVIDIA display going into Run Level 3 so I do believe that the initial graphics driver was loaded before going into Run Level 5. 

Unfortunately, when arriving at Run Level 5 the two displays attached to the second graphics card are not active.

Entering into a TTY and restarting the SDDM service does enable those two displays.

(I'll continue in another comment.)

While trying the sudo systemctl restart sddm work-around I discovered that it sometimes hangs - does not return to a prompt in the TTY. 

Checking from another TTY I saw that, when the restart command had hanged, there was another instance of SDDM in the background (ie: two instances running.)

So the better work-around is to stop sddm completely so that it can do whatever cleanup work it needs to do, then start sddm again when the TTY prompt returns, ie:

sudo systemctl stop sddm

(wait for the graphical screen to exit so that the TTY prompt returns, then...)

sudo systemctl start sddm

Thanks again

I don't know which driver you're using for your nvidia cards and which internal GPU you're using (my guess would be Intel), but it may help to move the driver to 
 initrd so it can be started much earlier(usually intel driver is, but nvidia is not due to potential use of suse-prime). Also it may help to add sleeps to displayamanger script to workaround the timing issues.

OTOH I haven't heard of anyone yet using 7 monitors successfully, let alone with 3 gfx cards by using a standard KDE desktop configuration. So I hope you can live with a workaround.

(In reply to Stefan Dirsch from comment #8)
> I don't know which driver you're using for your nvidia cards 

NVIDIA commercial drivers

> and which internal GPU you're using (my guess would be Intel), 

Intel UHD Graphics 630

> OTOH I haven't heard of anyone yet using 7 monitors successfully, let alone
> with 3 gfx cards by using a standard KDE desktop configuration. 

6 monitors (normally)

One day I plugged in an old monitor... and it worked! So I pulled another old monitor out and plugged it in... and it worked... Wonderful, isn't it? :)

I'm assuming I should send my great thanks - Thank you! - to people you probably know.

Sometimes when I'm changing settings on the motherboard I need to see what's showing on the on-board video card. I've got it plugged into an alternate input on one of the monitors. I was shocked today when I tried the Plasma 6 Wayland session and found that the Display Settings page was able to detect and manage all 6 monitors with the Intel card appearing as a 7th. For sure the software will continue to improve and all will be working one day soon.

Many of us have old monitors in storage. As more people find out that some of their video cards now support lots of monitors, people will pull their old monitors out and try them. It may be that 6 monitors may quickly become a common configuration.

> So I hope you can live with a workaround.

Yes, thanks. This is fine - I don't reboot terribly much.

Thanks again for your most excellent service. All the best

Ok. I'm glad I could be of some help. Closing.

(In reply to Sam Azer from comment #7)
> While trying the sudo systemctl restart sddm work-around I discovered that
> it sometimes hangs - does not return to a prompt in the TTY. 

And another problem: Sometimes sudo systemctl stop sddm returns to the TTY instantly but SDDM remains in the background :(

Turns out it's not that easy to shut down sddm. Seems it's best to tell it to stop and then check to see if it stopped - and perhaps even manually kill it - before trying to start it again.

HTH

SOLVED:

* Turns out that you can simply delete any old /etc/X11/xorg.conf file you may have remaining in your system. X and the NVIDIA drivers are now able to configure the system without using the xorg.conf file.

* Once I did this (removed the /etc/X11/xorg.conf file,) my system works perfectly. I boot and the LCD panels connected to the 2nd NVIDIA graphic card work fine. It's no longer necessary to apply any work-around.

Thank you all for your most excellent service.