You can use Device Tree Overlay feature to enable/disable some hardware functions without to recompile the kernel source code.

The dtbo files are stored in directory /boot/dtb/amlogic/kvim4.dtb.overlays:

khadas@Khadas:~$ ls -al /boot/dtb/amlogic/kvim4.dtb.overlays/
total 28
drwxr-xr-x 2 root root 4096 Jul  6 14:55 .
drwxr-xr-x 3 root root 4096 Jul  6 14:55 ..
-rwxr-xr-x 1 root root  462 Jul  6 14:55 ext_board.dtbo
-rwxr-xr-x 1 root root  223 Jul  6 14:55 i2cm_a.dtbo
-rwxr-xr-x 1 root root  223 Jul  6 14:55 i2cm_f.dtbo
-rwxr-xr-x 1 root root  225 Jul  6 14:55 pwm_f.dtbo
-rwxr-xr-x 1 root root  225 Jul  6 14:55 uart_e.dtbo

The releated dtbo configuration file is /boot/dtb/amlogic/kvim4.dtb.overlay.env

khadas@Khadas:~$ ls /boot/dtb/amlogic/kvim4.dtb.overlay.env 
/boot/dtb/amlogic/kvim4.dtb.overlay.env

If you want to enable some functions, you can edit the dtbo configuration file /boot/dtb/amlogic/kvim4.dtb.overlay.env and add the dtbo name to node fdt_overlays.

For example, if you want to enable I2CM_F, you can edit /boot/dtb/amlogic/kvim4.dtb.overlay.env and add i2cm_a to node fdt_overlays.

khadas@Khadas:~$ cat /boot/dtb/amlogic/kvim4.dtb.overlay.env 
fdt_overlays=i2cm_a

Save the file and reboot the system to take effect.

There are some ready to use dtbo files, you can also add your own dtbos to enable or disable the peripherals.

khadas@Khadas:~$ ll /boot/dtb/overlays/kvim3

• Write your own device tree overlay file, for example `example.dts`:

  /dts-v1/;
  /plugin/;
  
  / {
      fragment@0 {
          target = <&i2c3>;
  
          __overlay__ {
              status = "okay";
          };
      };
  };

This device tree overlay is to enable `i2c3`.

• Compile it to dtbo

  khadas@Khadas:~$ dtc -I dts -O dtb -o example.dtbo example.dts
  khadas@Khadas:~$ ls example.dtbo
  example.dtbo

• Move the dtbo file to /boot/dtb/overlays/kvim3

• Edit /boot/env.txt to add in node overlays

• Reboot the board