Hi there,
I am using Nvidia Jetson Orin Nano (developer kit). I’m forcing a custom EDID through the xorg.conf (“CustomEDID” “GPU-0.DFP-0:/EDIDfile.bin”) to be read by a DS90UH983-Q1EVM Serialiser through its displayport. I need to set the Hsync and Vsync to negative
Reading the Main Stream Attribute registers on the serialiser (DisplayPort info sent from Nvidia), I can see that the Hsync and Vsync are being read as negative when the EDID on the Nvidia is set positive.
I adjusted the EDID to set Hsync positive and Vsync negative as a test, and the registers returned as 0,1 (seems to be inverted?). The Serialiser datasheet outlines that 1 means the DP is sending it a positive polarity.
To see the effects, I set both Hsync and Vsync to negative and the seraliser read both polaritys as positive - which is what I want.
This, however, leads to the below issues where I am unable to SSH through the USB C as well as the mouse and keyboard stopped working for the first 10-15 seconds on login after which, it was fine.
Below are the dmesg logs.
l4tbr0: port 1 (usb0) entered blocking state
l4tbr0: port 1 (usb0) entered disabled state
device usb0 entered promiscuous mode
usb usb2-port2: Cannot enable. Maybe the USB cable is bad?
usb usb2-port2: config error
Above log is repeated
Question: Why do I have to set the polarity to negative for the DS90UH983-Q1EVM Serialiser to read it as positive?
Question: Why does Hsync & Vsync negative cause issues with the USB?
Jetpack 36.4.0 - installed via SDK manager.