i.MX93 Cortex-M33 j-link lost connection when Linux starts on A55 core

[Z2025121]

Hi,

I have an issue where the J-Link loses the connection to the Cortex-M33 core when Linux kernel starts on the Cortex-A55 core. The rpmsg between A55 and M33 still works. It seems that only the debugger has lost the connection. Re-attaching the debugger to the target fails.

Board: iMX93EVK

Cortex-M33 image: The multicode example code: rpmsg_lite_pingpong_rtos or
rpmsg_lite_str_echo_rtos from mcuxpresso SDK 2.14.2, 2.15.0 or 2.16.0 (tried all of them)

Debugger: Segger J-Link Untra+

Cortox-A55 image: Real-Time-Edge 2.8 (the Cortex-M33 code is similar to the mcuxpresso SDK 2.14.2)

Any ideas?

Thanks.

[Z2025121]

Hi,

Thanks for the tip.

The imx93-11x11-evk.dtb file is now generated with lpuart5 "disabled" as mentioned in the AN14120. However, the problem still exists. When the kernel starts, J-Link loses its connection to the target.

Just to be sure, I converted the imx93-11x11-evk.dtb back to a dts file and looked at it. lpuart5 is indeed "disabled".

But now I notice that when using the rpmsg examples, it actually loads a different dtb. u-boot: setenv fdtfile imx93-11x11-evk-rpmsg.dtb. This imx93-11x11-evk-rpmsg.dts does not use lpuart5 either.

BR

[Zhiming_Liu]

Hi @Z2025121 

For jlink debug, please refer this AN: https://docs.nxp.com/bundle/AN14120/page/topics/prepare_the_boards_for_the_debugger.html

Best Regards
Zhiming

[Z2025121]

Dear Zhiming,

Many thanks for the hints.

To disable the lpuart5 in devicetree I used the methods suggested in the AN14120. The suggested approach in the Application Note does not directly work for a Yocto build kernel-source as the .config file is missing. Any easy way to fix that?

I am using real-time-edge version 2.9

BR

[Zhiming_Liu]

Hi

You can try to use 'devtool modify real-time-edge-linux ' to unzip kernel source into build/workspace/sources/*, then modify code.

Best Regards
Zhiming

[Z2025121]

Many thanks. I will try it after updating real-time-edge to 2.9.