EHCI(4)

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 con-
     trollers (i.e., ohci(4) or uhci(4)) handling USB 1.x devices.  Conse-
     quently each USB connector is electrically connected to two USB con-
     trollers.	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.

     Currently there is no support for hubs that are connected with high speed
     upstream and low or full speed downstream (i.e., for transaction transla-
     tors).

     There is also no support for interrupt or isochronous transfers.