Jetson AGX Thor DevKit J81 Ethernet gadget negotiates only USB 2.0 High-Speed instead of SuperSpeed

Robotics & Edge Computing Jetson Systems Jetson Thor
1

Hello NVIDIA team,

We configured Ethernet-over-USB (CDC ECM) on the J81 USB-C port of a
Jetson AGX Thor Developer Kit (P4071-0000 + P3834-0008).

The network connection works, but the host PC always detects only USB 2.0
High-Speed:

Driver=cdc_ether, 480M

The PC port and cable support USB 3.2. The connection is direct, without a
hub. Reversing the USB-C cable does not change the result. J81 is physically
operational: in host mode, a connected hub negotiates 5000M.

Software version:

R38.4.0, GCID: 43443517

UDC diagnostics:

current_speed: high-speed
maximum_speed: super-speed
state: configured
gadget max_speed: super-speed-plus
role: device
phy-names: usb2-0, usb3-1

Temporary kernel diagnostics show that the USB3 PHY is powered on
successfully, but xUDC still connects only at High-Speed:

USB3 lane 1 companion 0 mode 3: SS_PORT_CAP=0x131
USB3 lane 1 powered on: ELPG_PROGRAM_1=0xfc0
device mode on: USB3 PHY=0
port connect: ... speed-field=0x3

The XUSB firmware is loaded correctly:

Firmware timestamp: 2025-09-08 05:45:00 UTC, Version: 90.05 release
Host supports USB 3.2 Enhanced SuperSpeed

Questions:

  1. Is SuperSpeed gadget mode supported on J81 with R38.4.0?
  2. Is any additional DTS configuration or CYPD8225 firmware update required?
  3. Is this a known limitation, and is a BSP fix planned?

Thank you.

3

Hi,
Is it enumerated correctly if you connect to either type-A port? By default the port is configured to device mode only and there is a patch to enable OTG mode:
Jetson Thor set RCM to host mode - #4 by DaneLLL

However, it looks to have stability issue. Would suggest connect to the type-A port and see if it works as expected.