NAME    [Toc]    [Back]

     ehci -- USB Enhanced Host Controller driver

SYNOPSIS    [Toc]    [Back]

     device ehci

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

     The ehci device driver first appeared in FreeBSD 5.1.

BUGS    [Toc]    [Back]

     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 translators).


     There is also no support for interrupt or isochronous transfers.


FreeBSD 5.2.1		       November 5, 2001 		 FreeBSD 5.2.1