.\" $NetBSD: ehci.4,v 1.11 2004/06/22 09:12:48 wiz Exp $
.\"
.\" 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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.\" $DragonFly: src/share/man/man4/ehci.4,v 1.2 2004/08/19 09:36:47 asmodai Exp $
.\"
.Dd June 22, 2004
.Dt EHCI 4
.Os
.Sh NAME
.Nm ehci
.Nd USB Enhanced Host Controller driver
.Sh SYNOPSIS
.Cd "device 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 HISTORY
The
.Nm
driver appeared in
.Dx 1.0 .
.Sh BUGS
There is no support (yet) for hubs that are connected with high speed upstream
and low or full speed downstream (i.e., for transaction translators).
.Pp
There is no support (yet) for interrupt or isochronous transfers.