DP to dual HDMI no display on Orin NX custom board

We made an Orin NX carrier board which support dual HDMI ports with DP to dual HDMI bridge IC, but currently no display output.
By chip vendor analysis, the DPRX link training is done and the bridge IC is ready to receive video stream, but no video stream output from source (Orin NX SoM) until timeout, and the bridge IC keep re-training continuously but always no video stream output from SoM. Please check the attached files for details and give us some suggestion, thanks.
DP to dual HDMI issue analysis 20240531.pdf (1.5 MB)
DP_failed_log_2024_06_03 1.txt (73.9 KB)

We don’t support such bridge. Only DP-MST hub to DP is tested.

We tried to rework a DP connector to the input side of the bridge IC on our customer board and put DP video output to it for test, the dual HDMI output can work with no problem. So, the bridge IC on our custom board can receive DP-MST traffic and output dual HDMI video correctly. Could you give us some suggestion why the NX SOM doesn’t send DP output? Or how can we ensure the NX SOM do send DP output? Thanks.
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Did you modify any device tree setting on your board? How did yo flash your board?

We don’t change any device tree setting related to display, and here below is how we flash our board, thanks.

sudo ./tools/kernel_flash/l4t_initrd_flash.sh --external-device nvme0n1p1 -c tools/kernel_flash/flash_l4t_external.xml -p "-c bootloader/t186ref/cfg/flash_t234_qspi.xml" --showlogs --network usb0 jetson-orin-nano-devkit internal

Then by default it is already sending DP signal.

Maybe this post would help.

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