/share/man/man4/ehci.4
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- .\" $NetBSD: ehci.4,v 1.8 2001/11/21 17:22:56 augustss Exp $
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- .\" Copyright (c) 2001 The NetBSD Foundation, Inc.
- .\" All rights reserved.
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- .\" This code is derived from software contributed to The NetBSD Foundation
- .\" by Lennart Augustsson.
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- .\" $FreeBSD$
- .\"
- .Dd March 4, 2012
- .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 xhci 4 ,
- .Xr ohci 4 ,
- .Xr uhci 4 ,
- .Xr usb 4
- .Sh HISTORY
- The
- .Nm
- device driver first appeared in
- .Fx 5.1 .
- .Sh LOADER TUNABLES
- When the kernel has been compiled with
- .Cd options USB_DEBUG ,
- some tunables become available that affect the behavior of
- .Nm .
- These tunables can be set at the
- .Xr loader 8
- prompt before booting the kernel or stored in
- .Xr loader.conf 5 .
- .Bl -tag -width "xxxxxx"
- .It Va hw.usb.ehci.lostintrbug
- This tunable enables the lost interrupt quirk.
- The default value is 0 (off).
- .It Va hw.usb.ehci.iaadbug
- This tunable enables the EHCI doorbell quirk.
- The default value is 0 (off).
- .It Va hw.usb.ehci.no_hs
- 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.
- The default value is 0 (off).
- .El