Rockpi 4 Android and Uart4

Hi all

We are working on Android 9 and want to use uart4, but we don’t know how to enable uart4.
We follow the reference( but can’t find anything.

please help us.

check the files:

after changes you need to recompile the Kernel

We have downloaded the source code from but can’t find the files you said in kernel.
Do we replace it with new kernel from radxa/kernel?

the main file is:


there you´ll find other includes like

#include "rk3399.dtsi"
#include "rk3399-android.dtsi"
#include "rk3399-opp.dtsi"
#include "rk3399-vop-clk-set.dtsi"

the preffered UART overlay file should be added after " #include “rk3399-android.dtsi”
make also shure you define “/dev/ttyS4” with the needed rights to your “ueventd.rockchip.rc” file
and you might also change the bootargs console parameter in file rk3399-rockpi-4b.dts