belfastraven

It looks like you are using the dts name from the kernel rather than u-boot. I believe for u-boot the dts name is something like arch/arm/dts/rk3399-rock-pi-4.dtsi -- it looks like there are a couple that might be the one you want--. The kernel dts files and u-boot dts files don't use the same paths .... You created a patch for the kernel, not u-boot.....