.\" $OpenBSD: ehci.4,v 1.5 2005/03/13 05:05:02 dlg Exp $
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.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Lennart Augustsson.
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.Dd October 27, 2004
.Dt EHCI 4
.Os
.Sh NAME
.Nm ehci
.Nd USB Enhanced Host Controller driver
.Sh SYNOPSIS
.Cd "ehci* at cardbus?"
.Cd "ehci* at pci?"
.Cd "usb*  at ehci?"
.Sh DESCRIPTION
The
.Nm
driver provides support for the USB Enhanced Host Controller Interface,
which is used by USB 2.0 controllers.
.Pp
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.,
.Xr ohci 4
or
.Xr 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.
.Sh SEE ALSO
.Xr cardbus 4 ,
.Xr ohci 4 ,
.Xr pci 4 ,
.Xr uhci 4 ,
.Xr usb 4
.Sh BUGS
The driver is not finished and is quite buggy.
.Pp
There is no support (yet) for isochronous transfers.