Orin nano DP1_HPD question

[ruei_chang]

Hello,

Our team is working on our board with Orin Nano SOM. And we are trying to output the DP1 signal to a LVDS IC which is RTD2136R.

We can see there is a logo from the begining. And after booting done, the screen becomes black. In the meantime, we can see the backlight is still working.

I pluged-in-out the HPD on our board and checked my Xorg.0.log. The message showed me only the DFP-0 is changed. The DFP-1 status always disconnected.
Our /var/log/Xorg.0.log

And there is a strange thing is I checked the card1-DP-1 status. It showed me connected. That doesn’t make sense.

root@tegra-ubuntu:/sys/class/drm/card1-DP-1# cat status
connected

Also I do another test.I put the same ssd on Nano devkit. Then pluged-in-out the DP-to-HDMI cable again. The Xorg.0.log showed me only the DFP-1 is changed.
Nano devkit /var/log/Xorg.0.log

Also the card1-DP-1 status is still connected.

root@tegra-ubuntu:/sys/class/drm/card1-DP-1# cat status
connected

Do we have misunderstood on DP1 design?

My Jetpack version
R36 (release), REVISION: 4.0, GCID: 37537400, BOARD: generic, EABI: aarch64, DATE: Fri Sep 13 04:36:44 UTC 2024

[WayneWWW]

HI,

If you use native DP cable on Orin Nano, then it will give you DP-1 status change as well.

[ruei_chang]

Does it mean that we do not need to be concerned about which DFP is connected? Once the /sys/class/drm/card1-DP-1/status changes and AUX_P/AUX_N receive the proper EDID, the DP1 signal should function correctly?"

[WayneWWW]

Yes you don’t need to care about that.

[ruei_chang]

Dear Wayne,
Just wanted to follow up on the DP issue again. We’re still seeing problems with the communication between the DP and the RTD2136R.

We had the chip vendor check the AUX signal. They found that the Nano queried the EDID from the RTD2136R, and the RTD2136R sent it back for sure.

But it looks like the Nano doesn’t get the proper EDID, so it’s trying to query it several times.

Then, the Nano stops asking and goes into DFP-0 in NVIDIA auto-select mode (640x480).

Any ideas on what might be causing this? The RTD2136R is set to 1920x1080p60. Does the Nano’s DP support this resolution?

Edid from Nano

Edid from RTD2136R

[WayneWWW]

Just a suggestion first. If you want to share a log, could you just attach full log as attachment instead of such screenshot?

And back to the question itself, is the EDID shown in the xorg log the one that RTD2136R provided to you? or it is not? It is hard to read what is the EDID from RTD2136R based on your screenshot.

[ruei_chang]

Dear Wayne,

Here are the logs. I hope these help.

1. Nano xorg log

2. RTD2136R log

[WayneWWW]

Could you just tell what is the exact EDID that your RTD2136R provided? I am not sure if I can interpret your i2c data flow correctly by reading such trace?

[ruei_chang]

Thank you, Wayne.
After reviewing the EDID files, we determined that the RTD2136R’s 128-byte EDID is insufficient for the Orin Nano’s DP, which requires 256 bytes to function correctly.