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     ehci — USB Enhanced Host Controller driver


     device ehci


     The ehci driver provides support for the USB Enhanced Host Controller
     Interface, which is used by USB 2.0 controllers.

     EHCI controllers are peculiar in that they can only handle the USB 2.0
     protocol.  This means that they normally have one or more companion
     controllers (i.e., ohci(4) or uhci(4)) handling USB 1.x devices.
     Consequently each USB connector is electrically connected to two USB
     controllers.  The handling of this is totally automatic, but can be
     noticed since USB 1.x and USB 2.0 devices plugged in to the same
     connector appear to connect to different USB busses.


     ohci(4), uhci(4), usb(4)


     The ehci device driver first appeared in FreeBSD 5.1.


     The driver is not finished and is quite buggy.

     There is currently no support for isochronous transfers.