Called by hcd if the root hub lost vbus power
void usb_root_hub_lost_power(struct usb_device * rhdev);
rhdev
struct usb_device for the root hub
The USB host controller driver calls this function when its root hub is resumed and Vbus power has been interrupted or the controller has been reset. The routine marks rhdev as having lost power. When the hub driver is resumed it will take notice and carry out power-session recovery for all the “USB-PERSIST”-enabled child devices; the others will be disconnected.