Cyclone V: how to enable USB1 with a ULPI USB PHY (USB3320)?

I want to enable USB1 (USB 2.0 controller) of the Cyclone V in host-only mode. But Vbus is not present and no device is detected.

• A ULPI-compatible Microchip USB3320 USB PHY is connected to the Cyclone V with a ULPI interface. The CPEN pin of the USB3320 controls a power switch on the board. To enable the 5V Vbus voltage, used to power USB devices, the CPEN pin must be driven high. Its POR state is low.
• HPS_GPIO0 is connected to the active-low RESET# pin of the USB3320.
• To check if Vbus is on, I connected a mouse, that should light up when connected to a USB host.

The main DT file is socfpga.dtsi. I altered it a little in both Barebox and Linux v6.6.22:

&usbphy0 {
	reset-gpios = <&porta 0 GPIO_ACTIVE_LOW>;
	status = "okay";
};

&usb1 {
	status = "okay";
	dr_mode = "host";
};

Barebox shows that GPIO0 (RESET#) is an output and is high, which is OK:

barebox:/ gpioinfo ff708000.gpio@ff708000:[email protected]

GPIOs 454-482, chip ff708000.gpio@ff708000:[email protected]:
             dir val requested name                 label
  GPIO    0: out hi  active low                      soc:usbphy.of reset
  GPIO    1: in  lo  false
  GPIO    2: in  lo  false

Barebox shows that the dwc2 driver binds to usb1:

barebox@Enclustra Mercury+ SA2:/ drvinfo dwc2
Driver  Device(s)
--------------------
dwc2
        [email protected]

Linux boot log:

# dmesg | grep -Ei 'usb|dwc2'
[    0.042372] usbcore: registered new interface driver usbfs
[    0.042408] usbcore: registered new interface driver hub
[    0.042448] usbcore: registered new device driver usb
[    0.896138] usbcore: registered new interface driver usb-storage
[    0.920377] usbcore: registered new interface driver usbhid
[    0.932106] usbhid: USB HID core driver
[    1.086689] usb_phy_generic soc:usbphy: dummy supplies not allowed for exclusive requests
[    1.095129] dwc2 ffb40000.usb: supply vusb_d not found, using dummy regulator
[    1.111913] dwc2 ffb40000.usb: supply vusb_a not found, using dummy regulator
[    1.137639] dwc2 ffb40000.usb: DWC OTG Controller
[    1.142362] dwc2 ffb40000.usb: new USB bus registered, assigned bus number 1
[    1.149465] dwc2 ffb40000.usb: irq 48, io mem 0xffb40000
[    1.155604] hub 1-0:1.0: USB hub found

I was told that the "dummy regulator" messages are nothing to worry about.

More Linux commands:

# lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux 6.6.22 dwc2_hsotg DWC OTG Controller
# gpioinfo gpiochip0
gpiochip0 - 29 lines:
        line   0:      unnamed      "reset"  output   active-low [used]
        line   1:      unnamed       unused   input  active-high
        line   2:      unnamed       unused   input  active-high

Pastebin

• my configuration: https://paste.debian.net/hidden/77078877
• Buildroot defconfig: https://paste.debian.net/hidden/e8b1d0fc
• Linux defconfig: https://paste.debian.net/hidden/d578d0f9