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NAME

     ehci — USB Enhanced Host Controller driver

SYNOPSIS

     device ehci

DESCRIPTION

     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.

SEE ALSO

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

HISTORY

     The ehci device driver first appeared in FreeBSD 5.1.

BUGS

     The driver is not finished and is quite buggy.

     There is currently no support for isochronous transfers.