>> i assume you set this option in the config.txt? This shouldn't have any >> affect for the mainline kernel / DT. > I am aware of that... I include my config.txt on RPi4B for reference... arm_64bit=1 enable_uart=1 upstream_kernel=1 kernel=vmlinuz-5.10.0-5-rt-arm64 initramfs initrd.img-5.10.0-5-rt-arm64 disable_fw_kms_setup=1 disable_overscan=1 hdmi_enable_4kp60=1 Best regards, Ryutaroh Matsumoto