EHCI(4) Kernel Interfaces Manual EHCI(4) NAME ehci -- USB Enhanced Host Controller driver SYNOPSIS device ehci DESCRIPTION The ehci driver provides support for the USB Enhanced Host Controller In- terface, which is used by USB 2.0 controllers. EHCI controllers are peculiar in that they can only handle the USB 2.0 pro- tocol. This means that they normally have one or more companion con- trollers (i.e., ohci(4) or 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 dif- ferent USB busses. SEE ALSO ohci(4), uhci(4), usb(4) HISTORY The ehci device driver first appeared in FreeBSD 5.1. BUGS The driver is not finished and is quite buggy. Currently there is no support for hubs that are connected with high speed upstream and low or full speed downstream (i.e., for transaction transla- tors). There is also no support for interrupt or isochronous transfers. FreeBSD 5.2.1 November 5, 2001 EHCI(4)
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