102 lines
3.1 KiB
Groff
102 lines
3.1 KiB
Groff
.\" $NetBSD: ehci.4,v 1.8 2001/11/21 17:22:56 augustss Exp $
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.\"
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.\" Copyright (c) 2001 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Lennart Augustsson.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 4, 2012
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.Dt EHCI 4
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.Os
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.Sh NAME
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.Nm ehci
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.Nd USB Enhanced Host Controller driver
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.Sh SYNOPSIS
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.Cd "device ehci"
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for the
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.Tn USB
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Enhanced Host Controller Interface,
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which is used by
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.Tn USB
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2.0 controllers.
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.Pp
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.Tn EHCI
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controllers are peculiar in that they can only handle the
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.Tn USB
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2.0 protocol.
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This means that they normally have one or more companion controllers
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(i.e.,
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.Xr ohci 4
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or
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.Xr uhci 4 )
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handling USB 1.x devices.
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Consequently each
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.Tn USB
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connector is electrically connected to two
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.Tn USB
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controllers.
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The handling of this is totally automatic,
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but can be noticed since
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.Tn USB
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1.x and
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.Tn USB
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2.0 devices plugged in to the same
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connector appear to connect to different USB busses.
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.Sh SEE ALSO
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.Xr xhci 4 ,
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.Xr ohci 4 ,
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.Xr uhci 4 ,
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.Xr usb 4
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.Sh HISTORY
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The
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.Nm
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device driver first appeared in
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.Fx 5.1 .
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.Sh LOADER TUNABLES
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When the kernel has been compiled with
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.Cd options USB_DEBUG ,
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some tunables become available that affect the behavior of
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.Nm .
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These tunables can be set at the
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.Xr loader 8
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prompt before booting the kernel or stored in
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.Xr loader.conf 5 .
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.Bl -tag -width "xxxxxx"
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.It Va hw.usb.ehci.lostintrbug
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This tunable enables the lost interrupt quirk.
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The default value is 0 (off).
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.It Va hw.usb.ehci.iaadbug
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This tunable enables the EHCI doorbell quirk.
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The default value is 0 (off).
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.It Va hw.usb.ehci.no_hs
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This tunable disables USB devices to attach like HIGH-speed ones and will force all attached devices to attach to the FULL- or LOW-speed companion controller.
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The default value is 0 (off).
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.El
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