Rock64Pro and 4K resolution

[rrosenheim]

I just got a Rock64Pro and I installed DietPi (running MATE as the UI) on it.  Boots up just fine, but the video is standard HD (1920x1080).  I went into Control Centre and 4K resolution isn't even listed in the Resolution drop down.  Anyone have any suggestions on how I can get/enable 4K resolution?  

The monitor is 4K, and Rock64 running DietPi operates in 4K mode.  I'm using the Rock64Pro version of DietPi.

Thanks,

Richard

Here's an update.  I was able to find an article online which provided me with the following commands to switch to 4K mode:

    xrandr --newmode "3840x2160" 338.75 3840 4080 4488 5136 2160 2163 2168 2200 -hsync +vsync
    xrandr --addmode HDMI-1 "3840x2160"
    xrandr --output HDMI-1 --mode "3840x2160"

When executed in Terminal, the system will switch to 4K resolution.  And under Armbian Ubuntu, if I add those lines to ~/.profile, Ubuntu boots to 4K resolution.  When I tried adding those lines to ~/.profile under DietPi (with MATE as the UI), it doesn't work.  

I'm guessing that with DietPi/MATE, I need to add those lines to a different file.  Does anyone know which file I need to edit?

[Luke]

I just got a Rock64Pro and I installed DietPi on it.  Boots up just fine, but the video is standard HD (1920x1080).  I went into Control Centre and 4K resolution isn't even listed in the Resolution drop down.  Anyone have any suggestions on how I can get/enable 4K resolution?  

The monitor is 4K, and Rock64 running DietPi operates in 4K mode.  I'm using the Rock64Pro version of DietPi.

Thanks,

Richard

No clue which kernel they are using and how up-to-date their image is -- suggest asking in the DietPi forums.