Device trees is a mechanism for describing hardware commonly used in ARM and RISC-V systems, allowing the kernel to discover and configure hardware devices without changing the kernel driver code.
Unlike x86 systems, where the ACPI tables enable automatic hardware discovery and configuration, most ARM systems need to have their device tree modified to declare hardware changes.
Open the grub configuration file /etc/default/grub.
Find the line that starts with GRUB_DTB= and add the path to the device tree file, for example:
GRUB_DTB= dtbs/rockchip/xxx.dtb
Then update the grub configuration:
sudo grub-mkconfig -o /boot/grub/grub.cfg
Note: There can only be one DTB specified.
Edit the extlinux configuration file /boot/extlinux/extlinux.conf, find the line with fdt, for example:
fdt /dtbs/rockchip/xxx.dtb
Then reboot.
Note: There can only be one DTB specified.