[Jetson Xavier NX]UART with debug function consult

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

Dear Sir,

In the Jetson Xavier NX DevKit, It seems use the UART2 as a Debug port which will print the whole message while booting, the others UART[0:1] only begin to print message after(Include) login.

Is there any configuration could to change them, such as make UART1 as the Debug port to print the whole message…etc

Best Regards,
MOMO Chen

3

hello momo_chen,

there’re 3 UARTs available on Xavier NX,
UART0 to M2
UART1 to 40PIN
UART2 to debug

please also refer to developer guide,
you could modify environment configuration to Disable Console over UART .
thanks

4

Dear Jerry,

Sorry to reply late, I’ve seen this chapter about “Disable Console over UART”
But…I’m not try to improve the kernel boot time with remove UART.

My scenario is our product will try to design a Carrier Board. In our design so far, since we will use the UAR0/UART1 to design as Console.
But the UART2 will deign to connect with another Micro-Processor for communication.

But there is only the UART2[debug] will print the whole message since power-on( that indicate it will show the whole booting message which include cboot, Kernel…etc).

the UART1 print the message after kernel finish system initial and login.

We just want to confirm “Is that possible to configure the UART0/1 to act as the UART2(print message since power on)”

Best Regards,
MOMO Chen

5

hello momo_chen,

actually, it is not suggest to change UART2 (i.e. Debug UART) to general UART, because it’s reserve for kernel debug purpose.
you may refer to MB1-BCT configuration file,
please also check this Jetson/AGX Xavier Tegra Combined UART - eLinux.org for more details,
for exmaple,
$Linux_for_Tegra/bootloader/t186ref/BCT/tegra194-mb1-bct-misc-l4t.cfg

enable_combined_uart = 1;
spe_uart_instance = 0x2;
6

Dear Jerry,

Thanks for your suggestion, I’ve tried to tune the spe_uart_instance to 0x1(I’m assume 0x1 indicate UART1), but the whole NX devkit will not show any message that include HDMI, Is that my assume wrong about this parameter??

I’ve saw there’re some description about the MB1 configuration, but I think I don’t get those value’s meaning, Is there any document for those parameter info further??

I also found this link which situation might similar as us. (I’m still study it for external link)

According the poster mention about the dts file tegra194-p3668-common.dtsi, I’m wonder why is there only two serial configuration?
Is that indicate there is only enable UART1 and UART2 in NX-devkit?

Best Regards,
MOMO Chen

7

hello momo_chen,

you should disassembler the dtb file into text file to review the device tree configuration.
for example, $ dtc -I dtb -O dts -o xavier-nx.dts kernel/dtb/tegra194-p3668-all-p3509-0000.dtb
there’re three UARTs available,
i.e. uarta / serial@3100000 ; uartb / serial@3110000 ; uarte / serial@3140000 ;

9

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