Can you switch the usb2-companion port for USB 3.0 ports?

Can you switch the usb2-companion for the USB 3.0 port? Or is there a hardware requirement
on the Jetson modules (NX and Nano) that requires a specific USB 2.0 companion port?

I have a custom carrier board with only one USB Type A connector and one USB Type C connector.
I’m wanting to switch the “forced recovery” usb connection from the USB 2.0 Type A connector over to
the USB 3.0 Type C connector.

What if I switch the USB 2.0 ports (USB1 and USB0) on my custom carrier board?

So USB1 (SODIM D-/D+ Pins #115/#117) would no longer be the USB 3.0 companion port, but instead
connect to the USB Type A 2.0 host connector (no longer OTG). USB0 (SODIM D-/D+ pins #109/#111) will be
the new USB 3.0 companion port wired to the Type C connector (now becoming OTG).

Will this work? Can any usb 2.0 port be used as the 3.0 companion port?

Once I make the hardware change, the only device tree change I think I need is
in tegra194-p3668-common.dtsi, changing the nvidia,usb2-companion port to usb2-0 instead of usb2-1.

Hardware changes will involve moving usb2-0 to the Type C connector, becoming the new 3.0 companion port, and staying OTG in device tree. usb2-1 will be moved to the Type A connector and will stay set to “host” mode in device tree.

ports {
usb2-0 {
mode = “otg”;
status = “okay”;
usb2-1 {
mode = “host”;
status = “okay”;
usb2-2 {
mode = “host”;
vbus-supply = <&battery_reg>;
status = “okay”;
usb3-2 {
- nvidia,usb2-companion = <1>;
+ nvidia,usb2-companion = <0>;
status = “okay”;

Does this sound right?

  1. Just make sure usb0 is available for device mode in hardware so that it can be used for board flash. There is no software getting involved in this part because kernel is not up when triggering recovery mode,. which is one kind of usb device mode triggered by hardware.

  2. You can change any usb2-companion. Just make sure it meets your hardware design. Also, remember that every usb3 port must have a usb2-companion. Which means your usb3 hardware design must have a usb2 come along.

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