Xavier NX HDMI troubleshooting

[meta2022]

I tried to troubleshooting HDMI issue by using “edit-get”, but got the following from Xavier NX dev kit. Is there a way to check if EDID work? Thanks in advance for suggestions.
*sudo get-edid
This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
No EDID on bus 1
No EDID on bus 2
No EDID on bus 3
No EDID on bus 4
No EDID on bus 5
No EDID on bus 6
No EDID on bus 7
No EDID on bus 8
No EDID on bus 9
No EDID on bus 10
1 potential busses found: 0
Bus 0 doesn’t really have an EDID…
Couldn’t find an accessible EDID on this computer.
I’m sorry nothing was successful. Maybe try some other arguments
if you played with them, or send an email to Matthew Kern pyrophobicman@gmail.com.

[WayneWWW]

Share me the dmesg and I can tell you whether it gets read or not.

[meta2022]

Thanks for quick response. The “putty.log” was from serial console with a custom HDMI adapter which has no display from HDMI monitor:
putty.log (148.1 KB)
The “hdmi_working.txt” was from Xavier NX Dev Kit
hdmi_working.txt (4.2 KB)

It appears HPD was working for both units, but I’m not sure if EDID was working.

[WayneWWW]

Yes, it looks like a 1080p mode is getting read. I guess EDID is getting read correctly.

If your monitor does not show anything, please check the hardware design with our design guide document. Especially the order of lane0 and lane2.

[meta2022]

Thanks for quick response again. It’s weird that the same schematic was used for a batch of working HDMI adapters before. I’ll use an oscilloscope to check the signals.
One more question, how does CEC impact HDMI monitor? I have the same CEC circuit as the Dev kit, but I’m not sure how to check if CEC is working.

[WayneWWW]

Do you have the schematic to share?

[meta2022]

Schematics for HDMI is attached. One of working boards without the components for CEC installed is also working. It seems CEC is not important.
The working boards have 2 layer PCBs. The non-working boards have 4 layers PCBs.
I ordered some old 2 layer PCBs to check if the issue was due to PCB layout.
I’ll update after boards are built with old 2 layer PCBs. I’ll use the same components used for the non-working boards.
Thanks!

[kayccc]

@Trumany any comments? Thanks

[Trumany]

Please refer to below HDMI example in DG. I don’t understand the J13 connection on your board, which pins of module are the HDMI lines connected to? And there are no 499 pull-downs and MOSFET switch in your design.

[meta2022]

Thanks or your response. I tried to reduce number of components and considered 499 Ohm may not have significant impact for 100 Ohm terminated HDMI 1.0 signals. There are some HDMI designs without the 499 Ohm termination.
This is a HDMI daughter card for debugging. Our Xavier NX carrier cards do not need HDMI during normal operations.
I rebuild 2 layer boards according to my schematics and they worked.
The only difference is layout of 2 layers and 4 layers. I have a theory that trace width and spacing are more critical for 4 layer boards because the ground plane may have more attenuation if not matched.
All traces are short so 2 layer boards worked even without 100 Ohm impedance.