Enabling 4K@60Hz on a RPi 4 on Ubuntu 21.10 Impish Indri

I have a Raspberry Pi 4 with 8 GiB of RAM, connected to a 4K monitor (Dell U3818DW). Enabling 60 Hz refresh rate should be as easy as adding the hdmi_enable_4kp60=1 flag to /boot/firmware/config.txt.

But there seems to be a problem parsing the EDID information, because the resulting mode only affords 30 Hz.

Fortunately, we can program the mode ourselves:

# Enable 4K@60Hz, single monitor
hdmi_cvt=3840 1600 60 7

Note that core_freq has to be set to 600 in order to provide the necessary bandwidth for the mode. This is usually taken care of by setting hdmi_enable_4kp6h=1, but not in this case.

Tags raspberrypi linux firmware ubuntu
pancho horrillo
I do things with computers.