Updates seem to work but login screen and desktop very low resolution

[barfly]

I have tried a few times to update my Noble install, but every time it fails with the same result, 1024x768 resolution on both the login and desktop screens. The connection is from an HDMI cable from my computer in the loft to my Samsung 55" S95B in my lounge. The install is fine, login and desktops run at 1920x800 or 3840x2160 depending on scaling.

The GPU is an older GTX1600 Nvidia.

I have tried inserting

xrandr --output HDMI-1 --mode 1920x1080 --rate 59.94

Into /usr/share/sddm/scripts/xsetup

I have tried nvidia drivers 470, 580 and 595 and nouveau drivers all the same result.

But that does nothing.

My 26.04 install and Windows 11 work fine, and reverting back to an older backup of 24.04 works every time.

Updates kill my resolution, 50% of stuff is off-screen with no way to change the resolution.

Any ideas? I am fresh out of them.

Cheers Tony

[claydoh]

and reverting back to an older backup of 24.04 works every time.

The recent kernel bump to 7.0.0, I'd say. maybe the kernel module failed to build for the new kernel, for each criver you have tried? But you'd see errors about that.

You can just boot to the previous kernel in Grub for the moment.

I have no idea what is broken, as the kernel is the same one as in 26.04, and ostensibly the same nvidia drivers. Does the nvidia-settings tool offer anything for settings that has any effect?

Go into KInfoCenter and see what driver is loading, compared to what it shows in 26.04.

[barfly]

claydoh You set me thinking. As an ex tv engineer, logical fault-finding is second nature to me, so I applied some logic and got it working.


Working Noble originally

Kernel ↓ NVIDIA module ↓ nvidia_drm ↓ GTX 1660 DP output ↓ Yamaha RX-V481 ↓ Samsung S95B

Broken after update

Kernel 6.17.0-35 ↓ No matching NVIDIA kernel module ↓ nouveau/modesetting fallback ↓ llvmpipe ↓ 1024x768 generic display

Working now

Kernel 7.0.0-28 ↓ linux-modules-nvidia-580-open-7.0.0-28 ↓ nvidia 580.173.02 ↓ DP-1 detected ↓ 1920x1080 Samsung QBQ95 ↓ hardware acceleration


So my steps were eliminate hardware, as I have a weird system, GTX1660 - displayport adaptor to HDMI to Yamaha RX -V 481 amplifier to Samsung S05B 55" HDMI all eliminated.

See what bit of the update broke the chain-

• prove the hardware path,
• prove the GPU is detected,
• prove the driver stack,
• locate the missing stage.

And so it all works beautifully on the 7 series kernel. Still stuffed on 6.17.0.35

The Kubuntu 24.04 update left the system in an inconsistent NVIDIA state:

• NVIDIA userspace packages were updated to:

nvidia-driver-580-open 580.173.02

• The 7.0 HWE kernel had the matching NVIDIA kernel modules:

linux-modules-nvidia-580-open-7.0.0-28-generic

• The older 6.17 kernels did not have usable NVIDIA modules:

linux-modules-nvidia-580-open-6.17.0-35-generic Installed: (none)

• Therefore the system fell back to:
  • nouveau / modesetting
  • llvmpipe
  • no real NVIDIA DRM connectors
  • no DP output through the Yamaha AVR

Once I booted the 7.0 kernel, the proper chain returned:


NVIDIA kernel module ↓ nvidia_drm ↓ GTX 1660 DisplayPort ↓ DP-HDMI adapter ↓ Yamaha RX-V481 ↓ Samsung S95B

I'll mark it as solved Claydoh thanks for setting me on the right track.

EDIT: Unable to find where to mark it as solved!

Cheers Tony

[oshunluvr]

Go to your first post and click "Edit" in lower left. Then the top bar of the left has the pull-downs to mark a SOLVED or whatever...