[Post-Install] Monitor is going to sleep after splash screen

[srllucas]

Hi everyone,

I have an issue with KDE + Wayland (X11 works normally). I can’t run any recent KDE + Wayland distribution (KDE + Wayland + Debian 12 is ok (kernel 6.1)).

ISSUE: After the splash screen, the monitor goes to sleep. The system itself is still running — for example, I can access it through TTY (and the monitor wakes up again after switching to a TTY). In KDE, there is no active display in "echo $DISPLAY" (it returns blank).

GNOME works normally, and I’m currently using Ubuntu 26.04 LTS (even though I love Kubuntu!).

My setup:

System:
Host: luciano-X99-B9 Kernel: 7.0.0-15-generic arch: x86_64 bits: 64
Desktop: GNOME v: 50.1 Distro: Ubuntu 26.04 (Resolute Raccoon)
Machine:
Type: Desktop Mobo: MACHINIST model: X99 B9 serial: <superuser required>
Firmware: UEFI vendor: American Megatrends v: 5.11 date: 06/07/2024
CPU:
Info: 14-core Intel Xeon E5-2680 v4 [MT MCP] speed (MHz): avg: 1200
min/max: 1200/3300
Graphics:
Device-1: Advanced Micro Devices [AMD/ATI] Ellesmere [Radeon RX
470/480/570/570X/580/580X/590] driver: amdgpu v: kernel
Display: wayland server: X.Org v: 24.1.10 with: Xwayland v: 24.1.10
compositor: gnome-shell driver: dri: radeonsi gpu: amdgpu
resolution: 1920x1080~60Hz
API: OpenGL v: 4.6 compat-v: 4.5 vendor: amd mesa v: 26.0.3-1ubuntu1
renderer: AMD Radeon RX 570 Series (radeonsi polaris10 ACO DRM 3.64
7.0.0-15-generic)
Info: Tools: api: eglinfo, glxinfo, vulkaninfo gpu: corectrl x11: xdriinfo,
xdpyinfo, xprop, xrandr
Network:
Device-1: Realtek RTL8111/8168/8211/8411 PCI Express Gigabit Ethernet
driver: r8169
Drives:
Local Storage: total: 1.35 TiB used: 63.36 GiB (4.6%)
Info:
Memory: total: 64 GiB available: 61.63 GiB used: 3.44 GiB (5.6%)
Processes: 497 Uptime: 25m Shell: Bash inxi: 3.3.40

[srllucas]

Update,

I’ve changed the monitor’s cable (I used to have a HDMI, and switched it by a DisplayPort). There is no issue anymore.

Thank you for the support.

[INVICTRA]

Before it loads up KDE you should see the login screen (SDDM). Can you confirm the login screen is showing up?

[srllucas]

Before it loads up KDE you should see the login screen (SDDM). Can you confirm the login screen is showing up?

The monitor goes to sleep before the SDDM... the splash apears in low resolution, than the video driver is loaded and it changes to high resolution... few seconds after, the monitor goes to sleep...

[die.boer]

At GRUB: Press e on the boot entry and add this to the linux line:

amdgpu.dc=0

Then boot with Ctrl+X.

If KDE Wayland then works we can make it permanant,let us know

[srllucas]

At GRUB: Press e on the boot entry and add this to the linux line:

amdgpu.dc=0

Then boot with Ctrl+X.

If KDE Wayland then works we can make it permanant,let us know

I already tried it... same behaviour

[die.boer]

ok next , from a TTY:
run these

mkdir -p ~/.config/environment.d

nano ~/.config/environment.d/kwin.conf​

put this inside KWIN_DRM_NO_AMS=1
save (ctrl+O - enter - ctrl+X) , and reboot

[INVICTRA]

Hi everyone,

I have an issue with KDE + Wayland (X11 works normally). I can’t run any recent KDE + Wayland distribution (KDE + Wayland + Debian 12 is ok (kernel 6.1)).

There is no X11 installed on a fresh Kubuntu 26.04 so I haven't tried this yet. It would be interesting to know if you could set SDDM to run in X11 and then try to continue to a Wayland desktop.

[srllucas]

ok next , from a TTY:
run these

mkdir -p ~/.config/environment.d

nano ~/.config/environment.d/kwin.conf​

put this inside KWIN_DRM_NO_AMS=1
save (ctrl+O - enter - ctrl+X) , and reboot

Again, splash screen and monitor goes to sleep.
TTY stays available.

Another information is that I can’t use the live-pendrive mode without using the “safe graphics” mode. Without it, i have the same behavior.

I’m quite confused. I’ve installed the gdm3 over kubuntu. It worked, and I’m able to access the system through the Ubuntu graphical interface. This sounds like the combination of kwin + my hardware + wayland holds the key of this issue.

[srllucas]

There is no X11 installed on a fresh Kubuntu 26.04 so I haven't tried this yet. It would be interesting to know if you could set SDDM to run in X11 and then try to continue to a Wayland desktop.

Yeah, X11 packages are not available in 26.04 repositories.

[srllucas]

At GRUB: Press e on the boot entry and add this to the linux line:

amdgpu.dc=0

Then boot with Ctrl+X.

If KDE Wayland then works we can make it permanant,let us know

This solution makes even TTY out...

[oshunluvr]

Yeah, X11 packages are not available in 26.04 repositories.

Yes, they are, just not installed by default:

sudo apt update
sudo apt install xorg -y
sudo apt install plasma-session-x11 -y

Then log out and select X11 session to log in.

[srllucas]

Yes, they are, just not installed by default:

sudo apt update
sudo apt install xorg -y
sudo apt install plasma-session-x11 -y

Then log out and select X11 session to log in.

I really didn't know that! For sure I will try it.

I didn’t find it before, for the reason I was searching in a live-pendrive session. Obviously, it wouldn’t find the package…

[oshunluvr]

Yes exactly. The ISO probably does not have X11 included.

[oshunluvr]

FYI, I tested desktop switching in a VM and it works, but going from X11 back to Wayland results in no panel in the Wayland session. I have to reboot to get a functional Wayland session.

[srllucas]

I will not try "wayland + kubuntu + my hardware" at this moment. I will keep using "Ubuntu + Wayland". Using X11 with 26.04 LTS can cause future problems too, once X11 is not the focus of Cannonical anymore. At least I've learn new things lol. Thank You all.

[srllucas]

Update,

I’ve changed the monitor’s cable (I used to have a HDMI, and switched it by a DisplayPort). There is no issue anymore.

Thank you for the support.

[Snowhog]

FYI, I tested desktop switching in a VM and it works, but going from X11 back to Wayland results in no panel in the Wayland session. I have to reboot to get a functional Wayland session.

Not the case with my laptop. Logging out from Wayland and logging in using X11 still gives me my panel, and vice versa.