Rockpi 4 Android and Uart4

samson · February 12, 2020, 6:39am

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(https://wiki.radxa.com/Rockpi4/hardware/devtree_overlays) but can’t find anything.

please help us.

n0tiert · February 12, 2020, 8:24am

check the files:

github.com

radxa/kernel/blob/release-4.4-rockpi4/arch/arm64/boot/dts/rockchip/rk3399-android.dtsi

/*
 * Copyright (c) 2016 Fuzhou Rockchip Electronics Co., Ltd
 *
 * This file is dual-licensed: you can use it either under the terms
 * of the GPL or the X11 license, at your option. Note that this dual
 * licensing only applies to this file, and not this project as a
 * whole.
 *
 *  a) This file is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU General Public License as
 *     published by the Free Software Foundation; either version 2 of the
 *     License, or (at your option) any later version.
 *
 *     This file is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 *
 * Or, alternatively,
 *

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github.com

radxa/kernel/blob/release-4.4-rockpi4/arch/arm64/boot/dts/rockchip/overlays-rockpi4/console-on-ttyS2-overlay.dts

// Definitions for setting uart4 pins as ttyFIQ0 console pins
/dts-v1/;
/plugin/;

/ {
	model = "ROCK PI 4B";
	compatible = "rockchip,rockpi","rockchip,rk3399";

	fragment@0 {
		target = <&uart2>;
		
		__overlay__ {
			status = "disabled";
		};
	};

	fragment@1 {
		target = <&fiq_debugger>;

		__overlay__ {

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github.com

radxa/kernel/blob/release-4.4-rockpi4/arch/arm64/boot/dts/rockchip/overlays-rockpi4/console-on-ttyS4-overlay.dts

// Definitions for setting uart4 pins as ttyFIQ0 console pins
/dts-v1/;
/plugin/;

/ {
	model = "ROCK PI 4B";
	compatible = "rockchip,rockpi","rockchip,rk3399";

	fragment@0 {
		target = <&uart4>;
		
		__overlay__ {
			status = "disabled";
		};
	};

	fragment@1 {
		target = <&fiq_debugger>;

		__overlay__ {

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after changes you need to recompile the Kernel

samson · February 13, 2020, 1:58am

We have downloaded the source code from https://github.com/radxa/manifests/tree/rockpi-box-9.0 but can’t find the files you said in kernel.
Do we replace it with new kernel from radxa/kernel?

n0tiert · February 13, 2020, 3:27am

the main file is:

/kernel/arch/arm64/boot/dts/rockchip/rk3399-rockpi-4b.dts

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

regards,

Brian