TX2's UART ISR handler

Robotics & Edge Computing Jetson Systems Jetson TX2
1

Looking for an example of Interrupt Service Routine to handle UART request.

3

Hi fa.arad,

Are you using the devkit or custom board for TX2?
What’s the Jetpack version in use?

I think the current UART driver will handle for interrupt by default.
Could you share the full device tree and dmesg from your board?

4

Hi Chunuaif,

I do not use the custom board for TX2 just the standard one that it comes with. The output of the ‘cat /etc/nv_tegra_release’ command is as follow:

cat /etc/nv_tegra_release

R32 (release), REVISION: 4.4, GCID: 23942405, BOARD: t186ref, EABI: aarch64, DATE: Fri Oct 16 19:37:08 UTC 2020

The current release does come with an ISR for the UART serial communication. I use the following setting for the serial port file descriptor:
/*
Function to configure the serial port
port=“/dev/ttyTHS2”,
baudrate=921600,
bytesize=serial.EIGHTBITS,
parity=serial.PARITY_NONE,
stopbits=serial.STOPBITS_ONE, )
*/

I use the ‘read ( file_descriptor, buffer, buffer_size)’ inside of a while loop to read the content, however, there is jitter in mili-seconds and I need to reduce it to micro-seconds. On TX2 Jetson’s all the UART ISRs go through core 0 and I can improve on it by writing a kernel module for the uart and isolate it to core 1/core 2 which are (optimized Denvers). This should help out. I wondering if somebody else has already done this and I could use their code as a starting point.

Best Wishes,
Faramarz Arad

5

There is no update from you for a period, assuming this is not an issue anymore.
Hence, we are closing this topic. If need further support, please open a new one.
Thanks ~0107

Have you tried to configure the smp_affinity for the UART interface for this use case?
Please also share the full dmesg for further check.