Samsung 5120x1440 monitor not correctly detected with kernel 6.17.0-20 and above, works fine with 6.17.0-19

Graphics / Linux Linux
1

Hardware:

  • Laptop: Lenovo with Ubuntu 24.04

  • GPU: NVIDIA GeForce RTX 3050

  • Driver: 580.126.09

  • External monitor: Samsung 49" (5120x1440)

  • Connection: Via a Lenovo ThinkPad docking station; the monitor is connected to the docking station via HDMI, reported as DP-3 by xrandr

Problem: Since a kernel update around April 1, 2026, my Samsung 5120x1440 external monitor is no longer correctly detected under kernel 6.17.0-20 and 6.17.0-22. The monitor appears as “Unknown 49’'” (6.17.0-20) or “Samsung Electric Company 49’'” (6.17.0-22) in the display settings and is limited to 3840x1080. Although the system treats the monitor as if it were running at 5120x1440, only the upper left portion of the desktop is actually displayed on the screen. Mouse cursor position is also misaligned accordingly.

The previous kernel 6.17.0-19 works perfectly with the same driver and the same hardware.

I have already tried the following without success:

  • Setting kernel module parameters: options nvidia-drm modeset=1, options nvidia-modeset hdmi_deepcolor=0, options nvidia-drm fbdev=1

I am currently working around the issue by booting with kernel 6.17.0-19, which I have pinned using apt-mark hold.

Is there a known fix or workaround for this regression?

2

Situation has changed with recent Linux firmware update (2026-04-28):

Title: Samsung 5120x1440 monitor scaled to 10240x2880 with kernel 6.17.0-22 and fractional scaling, worked fine with 6.17.0-19

Text: Hardware:

  • Laptop: Lenovo with Ubuntu 24.04

  • GPU: NVIDIA GeForce RTX 3050

  • Driver: 580.126.09

  • External monitor: Samsung LS49A950U 49" (5120x1440)

  • Connection: HDMI via Lenovo ThinkPad docking station (reported as DP-1-2.1.5 by xrandr)

Problem: Since a kernel update around April 1, 2026, my Samsung 5120x1440 external monitor is no longer correctly displayed under kernel 6.17.0-22. Although xrandr correctly reports 5120x1440 as the active resolution, GNOME treats the monitor internally as 10240x2880 (exactly double), so only the upper left portion of the desktop is visible on the screen. The mouse cursor position is also misaligned accordingly.

GNOME fractional scaling is enabled (experimental features: scale-monitor-framebuffer, x11-randr-fractional-scaling). The laptop’s built-in display uses 200% scaling, the Samsung monitor is set to 100%. This configuration worked perfectly for two years until the kernel update.

The monitors.xml is correctly configured:

  • Samsung LS49A950U: scale 1, mode 5120x1440 @ 59.977 Hz

  • Built-in display (eDP-1): scale 2, mode 3840x2400 @ 60 Hz

The EDID of the monitor is complete and correct. The 5120x1440 resolution is declared in Block 2 (DisplayID Extension Block).

The previous kernel 6.17.0-19 worked perfectly with the same driver and the same hardware. Kernel 6.17.0-19 no longer boots after a recent Linux firmware update.

Already tried without success:

  • Setting kernel module parameters: options nvidia-drm modeset=1, options nvidia-modeset hdmi_deepcolor=0, options nvidia-drm fbdev=1

  • xrandr --output DP-1-2.1.5 --scale 1x1 briefly showed the correct display but caused a crash after ~5 seconds

Note: The crash after xrandr --output DP-1-2.1.5 --scale 1x1 appears to be caused by GNOME automatically reverting the change after ~5 seconds without confirmation, not by the scaling command itself. The same crash reproducibly occurs in the display settings when a resolution change is not confirmed within the 15-second timeout.