Nx uart2 ths2

[rlatae123]

Hi

We are verifying PC and UART communication by disabling the debug port (/dev/ttyTCU0) and activating /dev/ttyTHS2 on the kernel dtb side.

Although stty can be used to communicate with the PC and Micro USB (CP2102) Uart, there is a symptom that the Uart signal is sometimes not transmitted from the NX side. When it was not transmitted, the stty command stopped in the terminal window, and when the waveform was observed with an oscilloscope in that state, no waveform was displayed.

We are using Jetpack 5.0.2. Is there anything that needs to be modified in terms of H/W or S/W for the above symptoms?

[KevinFFF]

Hi rlatae123,

Are you using the devkit or custom board for Xavier NX?

@rlatae123

We are verifying PC and UART communication by disabling the debug port (/dev/ttyTCU0) and activating /dev/ttyTHS2 on the kernel dtb side.

Please share your current dmesg for further check.

@rlatae123

We are using Jetpack 5.0.2. Is there anything that needs to be modified in terms of H/W or S/W for the above symptoms?

Are you trying to use Micro-USB port from your board for normal UART instead of debug UART?

Could you also verify with the latest JP5.1.2(R35.4.1)?

[rlatae123]

We’re testing on the carrier board

In the dmesg log, nothing is visible when the uart transmission fails.

We disable combined-uart and enable THS2 to pass UART2(DEBUG) signal to MICRO USB using CP2102 chip.

I’ll test it with 5.1.2

[rlatae123]

HI @KevinFFF

We ran the same test on 35.4.1, but the results were the same…

[KevinFFF]

What’s your use case for this UART?

Please share your device tree for further check.
and also the result of the following command on your board.

# cat /proc/cmdline

@rlatae123

disabling the debug port (/dev/ttyTCU0) and activating /dev/ttyTHS2 on the kernel dtb side

I would also like to do how you do this on your custom board.

[rlatae123]

we want use ths2 to general uart

device tree :
UART.txt (393.6 KB)

canlab@canlab-desktop:~$ cat /proc/cmdline 
root=/dev/mmcblk0p1 rw rootwait rootfstype=ext4 console=tty0 fbcon=map:0 net.ifnames=0 video=efifb:off nospectre_bhb 

uart test command

canlab@canlab-desktop:~$ sudo chmod 777 /dev/ttyTHS2 
canlab@canlab-desktop:~$ stty -F /dev/ttyTHS2 115200
canlab@canlab-desktop:~$ echo -n -e "hi" > /dev/ttyTHS2

error case :

[KevinFFF]

Could you use nvidia,tegra20-uart instead of nvidia,tegra186-hsuart for uartc@c280000?

	serial@c280000 {
-		compatible = "nvidia,tegra186-hsuart";
+		compatible = "nvidia,tegra20-uart";

Please also share the dmesg for further check.

[rlatae123]

I tested nvidia, tegra20-uart, it changed THS2 to S2
so I tested uart but same result

DMESG :
dmesg.log (68.9 KB)

[KevinFFF]

Please run the following command for UART loopback test.

# stty -F /dev/ttyS2 115200 raw -echo
# cat /dev/ttyS2 &
# echo "test" > /dev/ttyS2

[rlatae123]

Here is my test

is it right? what screen should i see?

[KevinFFF]

It seems the issue coming from the combined UART not disabled comepletely.
It might can not be disabled just through the device tree or configuration files.
Sorry that we don’t verify this use case so that please just use other UART interface for your use case.