usb_gadget_vbus_connect — Notify controller that VBUS is powered
int usb_gadget_vbus_connect (struct usb_gadget * gadget);
This call is used by a driver for an external transceiver (or GPIO) that detects a VBUS power session starting. Common responses include resuming the controller, activating the D+ (or D-) pullup to let the host detect that a USB device is attached, and starting to draw power (8mA or possibly more, especially after SET_CONFIGURATION).
Returns zero on success, else negative errno.