amdgpu and HDMI monitor makes x.org not work

[deathromantik]

I am trying to get my laptop using amdgpu to work using a second screen. However if I plug it in after logon and try to set up the monitor as anything other than a clone of the laptop display, it crashes and I end up at the SDDM login screen.
From there if I try to login it immediately crashes and sends me back to the go in screen. Unpluging the HDMI cable makes the the laptop screen go black
What I have tried to fix the problem:
1. boot with a kernel from the regular ubuntu repo rather than one I installed via ukuu
2. purge and roll back the amdgpu drivers from the ppaibaf/graphics-drivers ones to the ones that come with kubuntu
3. thinking it might be an SDDM bug I updated plasma via the kubuntu backports ppa
None of those worked.

So I tried installing on another partition this time with the HDMI monitor plugged in. Live USB booted with no problems, install worked. Reboot and both screens worked well. I then tried one step at a time to break the system to replicate the problem.
1. I updated the kernel to 4.16.3-041603-generic via Ukuu, reboot. It all works fine.
2. I tried updating to the ppa amdgpu drivers, reboot. Again works fine
3. I tried installing steam, rebooting and it still worked.
4. I updated KDE via the backports PPA, rebooted and still no problems.

Which has me thinking, just what is wrong with my main install of Kubuntu? How do I fix this?

uname -a                                                                                                                                                                                                                                                
Linux W4R-D3N 4.16.3-041603-generic #201804190730 SMP Thu Apr 19 07:32:02 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

lspci output:

00:00.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1450
00:00.2 IOMMU: Advanced Micro Devices, Inc. [AMD] Device 1451
00:01.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1452
00:01.3 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 1453
00:02.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1452
00:03.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1452
00:03.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 1453
00:04.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1452
00:07.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1452
00:07.1 PCI bridge: Advanced Micro Devices, Inc.

[AMD] Device 1454
00:08.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1452
00:08.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 1454
00:14.0 SMBus: Advanced Micro Devices, Inc. [AMD] FCH SMBus Controller (rev 59)
00:14.3 ISA bridge: Advanced Micro Devices, Inc. [AMD] FCH LPC Bridge (rev 51)
00:18.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1460
00:18.1 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1461
00:18.2 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1462
00:18.3 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1463
00:18.4 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1464
00:18.5 Host bridge: Advanced Micro Devices, Inc.

[AMD] Device 1465
00:18.6 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1466
00:18.7 Host bridge: Advanced Micro Devices, Inc. [AMD] Device 1467
03:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] USB 3.1 XHCI Controller (rev 02)
03:00.1 SATA controller: Advanced Micro Devices, Inc. [AMD] Device 43b7 (rev 02)
03:00.2 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b2 (rev 02)
04:00.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b4 (rev 02)
04:01.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b4 (rev 02)
04:04.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b4 (rev 02)
04:05.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b4 (rev 02)
04:06.0 PCI bridge: Advanced Micro Devices, Inc.

[AMD] Device 43b4 (rev 02)
04:07.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b4 (rev 02)
04:08.0 PCI bridge: Advanced Micro Devices, Inc. [AMD] Device 43b4 (rev 02)
06:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 10)
07:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device b822
0c:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480] (rev c1)
0c:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Device aaf0
11:00.0 Non-Essential Instrumentation [1300]: Advanced Micro Devices, Inc. [AMD] Device 145a
11:00.2 Encryption controller: Advanced Micro Devices, Inc. [AMD] Device 1456
11:00.3 USB controller: Advanced Micro Devices, Inc. [AMD] USB3 Host Controller
12:00.0 Non-Essential Instrumentation [1300]: Advanced Micro Devices, Inc.

[AMD] Device 1455                                                                                                                                                                                   
12:00.2 SATA controller: Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode] (rev 51)                                                                                                                                                                           
12:00.3 Audio device: Advanced Micro Devices, Inc. [AMD] Device 1457

Xorg.0.log,old: https://pastebin.com/nkZ7KmMg

[Snowhog]

Have you tried, with the laptop powered off, plugging in the HDMI monitor and then booting?

[deathromantik]

Yes, I have.

[vinnywright]

try deleting the " /home/you/.local/share/kscreen/" folder , reboot and try again .

VINNY

[deathromantik]

Yes, that fixed it, it all works now and it survived a reboot. Thank you very much.
In the interest of learning, any idea how and why it messed up like this?

[vinnywright]

Yes, that fixed it, it all works now and it survived a reboot. Thank you very much.
In the interest of learning, any idea how and why it messed up like this?

I'm not totally sure , but this is where "kscreen" keeps previously used settings and I do know that I got stuck with "unified" displays on my external (TV) and doing this fixed it for me .

glad it helped you

VINNY

[deathromantik]

I am guessing the installer does something wrong on laptops with my configuration, since results were totally different depending if I installed with the HDMI monitor plugged in or not. I might give it another test later on.