1.\" $NetBSD: ehci.4,v 1.8 2001/11/21 17:22:56 augustss Exp $ 2.\" 3.\" Copyright (c) 2001 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Lennart Augustsson. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.\" $FreeBSD$ 31.\" 32.Dd April 24, 2018 33.Dt EHCI 4 34.Os 35.Sh NAME 36.Nm ehci 37.Nd USB Enhanced Host Controller driver 38.Sh SYNOPSIS 39.Cd "device ehci" 40.Sh DESCRIPTION 41The 42.Nm 43driver provides support for the 44.Tn USB 45Enhanced Host Controller Interface, 46which is used by 47.Tn USB 482.0 controllers. 49.Pp 50.Tn EHCI 51controllers are peculiar in that they can only handle the 52.Tn USB 532.0 protocol. 54This means that they normally have one or more companion controllers 55(i.e., 56.Xr ohci 4 57or 58.Xr uhci 4 ) 59handling USB 1.x devices. 60Consequently each 61.Tn USB 62connector is electrically connected to two 63.Tn USB 64controllers. 65The handling of this is totally automatic, 66but can be noticed since 67.Tn USB 681.x and 69.Tn USB 702.0 devices plugged in to the same 71connector appear to connect to different USB buses. 72.Sh LOADER TUNABLES 73When the kernel has been compiled with 74.Cd options USB_DEBUG , 75some tunables become available that affect the behavior of 76.Nm . 77These tunables can be set at the 78.Xr loader 8 79prompt before booting the kernel or stored in 80.Xr loader.conf 5 . 81.Bl -tag -width "xxxxxx" 82.It Va hw.usb.ehci.lostintrbug 83This tunable enables the lost interrupt quirk. 84The default value is 0 (off). 85.It Va hw.usb.ehci.iaadbug 86This tunable enables the EHCI doorbell quirk. 87The default value is 0 (off). 88.It Va hw.usb.ehci.no_hs 89This 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. 90The default value is 0 (off). 91.El 92.Sh SYSCTL VARIABLES 93The following variables are available as both 94.Xr sysctl 8 95variables and 96.Xr loader 8 97tunables: 98.Bl -tag -width indent 99.It Va hw.usb.ehci.debug 100Debug output level, where 0 is debugging disabled and larger values increase 101debug message verbosity. 102Default is 0. 103.El 104.Sh SEE ALSO 105.Xr ohci 4 , 106.Xr uhci 4 , 107.Xr usb 4 , 108.Xr xhci 4 109.Sh HISTORY 110The 111.Nm 112device driver first appeared in 113.Fx 5.1 . 114