freebsd-dev/share/man/man4/ehci.4
Tom Rhodes 8e13d96bd9 Add a manual page for the USB Enhanced Host Controller Driver.
Submitted by:	ticso (who obtained the original version from NetBSD)
2003-05-18 19:55:39 +00:00

94 lines
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.\" $NetBSD: ehci.4,v 1.8 2001/11/21 17:22:56 augustss Exp $
.\"
.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Lennart Augustsson.
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.\" This product includes software developed by the NetBSD
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.\" $FreeBSD$
.\"
.Dd November 5, 2001
.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
.Tn USB
Enhanced Host Controller Interface,
which is used by
.Tn USB
2.0 controllers.
.Pp
.Tn EHCI
controllers are peculiar in that they can only handle the
.Tn 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
.Tn USB
connector is electrically connected to two
.Tn USB
controllers.
The handling of this is totally automatic,
but can be noticed since
.Tn USB
1.x and
.Tn USB
2.0 devices plugged in to the same
connector appear to connect to different USB busses.
.Sh SEE ALSO
.Xr ohci 4 ,
.Xr uhci 4 ,
.Xr usb 4
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 5.1 .
.Sh BUGS
The driver is not finished and is quite buggy.
.Pp
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).
.Pp
There is also no support for interrupt or isochronous transfers.