9.2.6.14.8 Receiving a Host Resume
In Suspend mode, a resume event on the USB bus line is detected asynchronously, transceiver and clocks disabled (however, the pullup should not be removed).
Once the resume is detected on the bus, the signal WAKE_UP in the UDPHS_INTSTA is set. It may generate an interrupt if the corresponding bit in the UDPHS_IEN register is set. This interrupt may be used to wake up the core, enable PLL and main oscillators and configure clocks.