How uart1/2 work with out overlay dtb file

We trying to building debian (
Kernel dts overlay does not contain uart1 and uart2 dts file.
Where uart1 and uart2 dts files is present ?
How uart1/2 work with out overlay dtb file ?
We want to use two uart at same time but uart1 rts/cts mux with uart2 we need to remove uart1 rts/cts pin from dts file.

Thanks & Regards

Any update on this? Please update soon.

How about using UART0 and UART2 at the same time? If this meets your need, you can try.

You need to do the following steps.

Use system image, rockpis_debian_buster_minimal_arm64_191219_0406-gpt.img

enable UART0 and UART2 in file, /boot/hw_intfc.conf


And comment this line in file, /boot/hw_intfc.conf


Delete the following strings of command line in file, cat /boot/extlinux/extlinux.conf

earlyprintk console=ttyFIQ0,1500000n8

And the final content is this.

root@rockpis:/# cat /boot/extlinux/extlinux.conf 
timeout 10
menu title select kernel

label kernel-4.4.143-34-rockchip-g3c9d2019dba7
    kernel /vmlinuz-4.4.143-34-rockchip-g3c9d2019dba7
    initrd /initrd.img-4.4.143-34-rockchip-g3c9d2019dba7
    devicetreedir /dtbs/4.4.143-34-rockchip-g3c9d2019dba7
    append  rw init=/sbin/init rootfstype=ext4 rootwait  root=UUID=ced8410b-05fb-4347-b0ae-ad2065c7d629

Reboot. and Use adb to access ROCK Pi S.

Hi @Stephen ,
We followed the steps mentioned by you.
But while using uart 0, receiving junk data and while sending also same issue.
Not able to get proper data.

Hi, Here is my test.

On ROCK Pi S, use adb

 stty -F /dev/ttyS0 raw speed 115200
 cat /dev/ttyS0

On Ubuntu Host, create and test.txt

$ cat 
# -*- coding: UTF-8 -*-
import serial
ser = serial.Serial("/dev/ttyUSB0")
ser.baudrate = 115200

$ python

You would see the content of test.txt on ROCK Pi S.

Would you mind doing the testing?

Hi @Stephen
I executed same commands as mentioned.
But still getting junk data as follows.

cat /dev/ttyS0
�i�i�a� �o�a�s�i�a�i�r�d�y�
�i�i�a� �o�a�s�i�a�i�r�d�y�

Here is my result.

root@rockpis:/test# uptime
 11:24:50 up  1:55,  0 users,  load average: 0.00, 0.00, 0.00
root@rockpis:/test# stty -F /dev/ttyS0 raw speed 115200
root@rockpis:/test# cat /dev/ttyS0 
ROCK Pi S is a Rockchip RK3308 based SBC(Single Board Computer) by Radxa. It equips a 64bits quad core processor, USB, ethernet, wireless connectivity and voice detection engine at the size of 1.7 inch, make it perfect for IoT and voice applications. ROCK Pi S comes in two ram sizes 256MB or 512MB DDR3, and uses uSD card for OS and storage. Optionally, ROCK Pi S can provide on board storage version with 1Gb/2Gb/4Gb/8Gb NAND flash. 

Make sure the Baudrate is right and do not use minicom or other serial tools for rockpis ttyS0.