Disable ttyS2 console on Radxa ROCK 4C+

[wittrup]

Hello

I want to disable console on /dev/ttyS2 on a Radxa ROCK 4C+ running

rock@rockpi-4cplus:/boot$ cat /etc/os-release | grep -v URL
PRETTY_NAME="Armbian 25.5.0-trunk.40 noble"
NAME="Ubuntu"
VERSION_ID="24.04"
VERSION="24.04 LTS (Noble Numbat)"
VERSION_CODENAME=noble
ID=ubuntu
ID_LIKE=debian
UBUNTU_CODENAME=noble
LOGO="armbian-logo"
ARMBIAN_PRETTY_NAME="Armbian 25.5.0-trunk.40 noble"

There are posts and other information out there.
For instance:
https://docs.armbian.com/User-Guide_Fine-Tuning/#how-to-toggle-boot-output
which leads to 
http://redsymbol.net/linux-kernel-boot-parameters/
 

rock@rockpi-4cplus:/boot$ grep console armbianEnv.txt
console=both

The information found so far, implies there are options like: none, serial, both, and another
But what is the another option?
So that I can disable console on /dev/ttyS2  and use that for other purposes.
Without compromising the Docs reccomandation: To disable console entirely (not recommended) set console to none
 

[SteeMan]

moved to correct forum and added the proper tag

[wittrup]

Thanks @SteeMan
Made me stumble upon something similar.

Found armbianmonitor

rock@rockpi-4cplus:~$ sudo armbianmonitor -u

Checked the log.

[    2.614818] ff180000.serial: ttyS0 at MMIO 0xff180000 (irq = 35, base_baud = 1500000) is a 16550A
[    2.616480] ff1a0000.serial: ttyS2 at MMIO 0xff1a0000 (irq = 36, base_baud = 1500000) is a 16550A

Changed armbianEnv.txt from:

console=both

To:

console=ttyS0

Then a reboot.  That didn't work.

So changing the boot.cmd from:

setenv console "both"

To:

setenv console "ttyS0"

Then 

mkimage -C none -A arm -T script -d /boot/boot.cmd /boot/boot.scr

and reboot.

ttyS2 console are still enabled.

Connections are verified by reading the connected pins after forcing communication

root@rockpi-4cplus:/home/rock# stty -F /dev/ttyS2 115200 cs8 -parenb -cstopb
root@rockpi-4cplus:/home/rock# while true; do echo -n "A" > /dev/ttyS2; sleep 0.25; done

Connected pins 8 & 10:
 

And log still says:

[ 2.615671] ff180000.serial: ttyS0 at MMIO 0xff180000 (irq = 35, base_baud = 1500000) is a 16550A
[ 2.616076] serial serial0: tty port ttyS0 registered
[ 2.617411] ff1a0000.serial: ttyS2 at MMIO 0xff1a0000 (irq = 36, base_baud = 1500000) is a 16550A
[ 2.617621] printk: legacy console [ttyS2] enabled

What would be the next step here?

[wittrup]

Continuing ...

root@rockpi-4cplus:~# cp /boot/dtb/rockchip/rk3399-rock-4c-plus.dtb rk3399-rock-4c-plus.dtb.backup
root@rockpi-4cplus:~# dtc -I dtb -O dts -o rk3399-rock-4c-plus.dts rk3399-rock-4c-plus.dtb.backup
rk3399-rock-4c-plus.dts: Warning (unit_address_vs_reg): /usb@fe800000: node has a unit name, but no reg or ranges property
rk3399-rock-4c-plus.dts: Warning (unit_address_vs_reg): /usb@fe900000: node has a unit name, but no reg or ranges property
rk3399-rock-4c-plus.dts: Warning (avoid_unnecessary_addr_size): /dsi@ff960000: unnecessary #address-cells/#size-cells without "ranges", "dma-ranges" or child "reg" property
rk3399-rock-4c-plus.dts: Warning (avoid_unnecessary_addr_size): /dsi@ff968000: unnecessary #address-cells/#size-cells without "ranges", "dma-ranges" or child "reg" property
rk3399-rock-4c-plus.dts: Warning (unique_unit_address): /pcie@f8000000: duplicate unit-address (also used in node /pcie-ep@f8000000)
root@rockpi-4cplus:~#
root@rockpi-4cplus:~# vi rk3399-rock-4c-plus.dts

rk3399-rock-4c-plus.dts is attached.
Here is the relevant sections I've found:

/ {
	model = "Radxa ROCK 4C+";

	aliases {
		serial2 = "/serial@ff1a0000";
	};

	serial@ff1a0000 {
		compatible = "rockchip,rk3399-uart\0snps,dw-apb-uart";
		reg = <0x00 0xff1a0000 0x00 0x100>;
		clocks = <0x08 0x53 0x08 0x162>;
		clock-names = "baudclk\0apb_pclk";
		interrupts = <0x00 0x64 0x04 0x00>;
		reg-shift = <0x02>;
		reg-io-width = <0x04>;
		pinctrl-names = "default";
		pinctrl-0 = <0x49>;
		status = "okay";
		phandle = <0xe7>;
	};

	__symbols__ {
		uart2 = "/serial@ff1a0000";
	};
};

What should I do to disable /dev/ttyS2 console?

rk3399-rock-4c-plus.dts