Help required to modify kernel on a rockchip device

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Hi everyone, I have to make a custom kernel for a RK3568 based device with kernel 4.19.232. Currently running Ubuntu 20.04LTS.

I followed this guide https://opensource.rock-chips.com/wiki_Rockchip_Kernel and I tried compiling 4.19 from rockchip source code and made a boot.img with the rk3568-evb1-ddr4-v10.dtb.

The device boots but HDMI isn't working correctly, LVDS appears detected but does not show anything and one USB stopped working.

 

Since I am new to all these things, does anyone know of any guides to compile kernels for rockchip ?

I am trying to replace the boot.img from the original FW because kernel is inaccessible and iptables is not working. Also, there are some issues with monitors flickering.