usb: dwc3: Set default mode for dwc_usb31

dwc_usb31 does not support OTG mode. If the controller supports DRD but
the dr_mode is not specified or set to OTG, then set the mode to
peripheral.
Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.c

@@ -78,6 +78,14 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
 			mode = USB_DR_MODE_HOST;
 		else if (IS_ENABLED(CONFIG_USB_DWC3_GADGET))
 			mode = USB_DR_MODE_PERIPHERAL;
+
+		/*
+		 * dwc_usb31 does not support OTG mode. If the controller
+		 * supports DRD but the dr_mode is not specified or set to OTG,
+		 * then set the mode to peripheral.
+		 */
+		if (mode == USB_DR_MODE_OTG && dwc3_is_usb31(dwc))
+			mode = USB_DR_MODE_PERIPHERAL;
 	}
 
 	if (mode != dwc->dr_mode) {