Title: crtc config fails when changing resolution with Xrandr from 4K
Tags: linux;ubuntu;resolution;xorg
Question: I am currently trying to change the resolution of my screen from 3840x2160 to 1920x1080. The screen is set to display 0 on output HDMI2. I am running an app via startx on display 0.
When I try to run xrandr -d :0 --output HDMI2 --mode 1920x1080 I receive the following error:  xrandr: Configure crtc 2 failed
When I run the same command with --verbose I receive the following output:
crtc 2: disable
xrandr: Configure crtc 2 failed
crtc 0: disable
crtc 1: disable
crtc 2: disable
crtc 3: disable
screen 0: revert
crtc 0: revert
crtc 1: revert
crtc 2: revert
crtc 3: revert
Any help here is greatly appreciated!


Here is another answer: I used this guide to set a custom resolution via the video kernel parameter. This worked for me on Wayland, but I had to be very careful about the aspect ratio. My panel has 3:2, so I had to choose a resolution that has the same ratio.
The important bits from this guide are:
Add video=HDMI2:1920x1080@60 to your kernel parameters
Depending on your boot-manager do the necessary steps to enable your changes
Restart PC
Change the resolution using the GUI of your window manager
I would recommend a lower resolution that is exactly half of the native resolution and let the display do the interpolation (which is the case when using 1920x1080). This way fonts should still look ok on your 4K panel, because then each &quot;virtual&quot; pixel is directly mapped to 4 native pixels on your screen. If you have very good vision then you probably will notice blur if the panel's interpolation is not very good.

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