USB Device Mode on RockPro64

[R0b0t1]

Hello, using the image provided at https://www.armbian.com/rockpro64/ the board works when booted via uSD card but not via MMC. There appears to be no device mode USB drivers installed. I pulled the kernel sources with `armbian-config` and compiled them myself making sure to select dual-mode support for the DWC2 and DWC3 drivers. The kernel boots after install, but I still see nothing in /sys/class/udc and am unable to see any dwc2/3 drivers (save dwc2_pci and some dwc3 i3c drivers).

 

I'm able to load libcomposite, the configfs driver, but that does not pull in a USB device mode driver. I'm unable to attach armbian monitor status right now but will update my post with it.

Board: Not on the list

[R0b0t1]

I made progress. The default device tree sets the first dwc3 controller as "otg." Unfortunately this seems to not have much effect. I've tried looking for a software switch and also tried plugging the board in as a device. How do you set this without needing a reboot?

 

Changing the two DWC3 nodes in the file "arch/arm64/boot/dts/rockchip/rk3399-rockpro64.dtsi:"

 

&usbdrd3_0 {
        status = "okay";
};

&usbdrd_dwc3_0 {
        status = "okay";
        dr_mode = "peripheral";
};

&usbdrd3_1 {
        status = "okay";
};

&usbdrd_dwc3_1 {
        status = "okay";
        dr_mode = "peripheral";
};

 

They are both listed in /sys/class/udc:

# ls /sys/class/udc
fe800000.usb  fe900000.usb

 

But, again, I'd like to change mode without needing to reboot. I'm also unsure how compatible the Type-C port is.

[R0b0t1]

I've some more observations. Checking the code in drivers/usb/dwc3/core.c I was

unable to find what actually allows you to select the mode if specifying OTG.

I have devices in /sys/class/udc and they function properly via configfs when
plugged into a USB2 only port. If I plug them into a superspeed port I get
nothing in dmesg on the host side. At first, I did get a response on the host, in
the form of:

[591550.770819] usb 1-1.2: new full-speed USB device number 76 using xhci_hcd
[591550.870962] usb 1-1.2: device descriptor read/64, error -32
[591551.078865] usb 1-1.2: device descriptor read/64, error -32
[591551.286875] usb 1-1.2: new full-speed USB device number 77 using xhci_hcd
[591551.386873] usb 1-1.2: device descriptor read/64, error -32
[591551.594859] usb 1-1.2: device descriptor read/64, error -32
[591551.703160] usb 1-1-port2: attempt power cycle

However now I get no driver activity when binding the UDC in configfs or
loading or unloading the respective modules. Kernel is 5.7.15 w/ patches.

It doesn't seem like bad USB-C wiring fried port or tripped a polyfuse, the

port still works after attempting USB3 device mode.

[flatmax]

I got this working on an M4B but should be the same for you.

fe800000.usb is USB phy 0

fe900000.usb is USB phy 1

 

Make sure you're setting up the UDC with the correct phy. When I setup my gadgets manually I do :

echo fe800000.usb > UDC # phy 0

 

This is the output of dmesg on my PC when I connect :

 

[970432.082528] usb 1-2.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[970432.082529] usb 1-2.3: Product: Ethernet/audio
[970432.082530] usb 1-2.3: Manufacturer: Audio Injector.net