At least on Orange Pi PC Plus even the host mode does not work without
enabling the phy and setting it to the host mode.
The driver will now parse dr_mode property and will try to configure
itself and the phy accordingly.
OTG mode is not supported yet, so it is treated as the device / peripheral
mode.
The phy is enabled -- powered on -- only for the host mode.
The device mode requires support from a phy driver, e.g., aw_usbphy on
Allwinner platform.
aw_usbphy does not support the device mode, so it cannnot work yet.
MFC after: 6 weeks
1668d773a4