DragonFly On-Line Manual Pages

EHCI(4) 	      DragonFly 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
     Interface, which is used by USB 2.0 controllers.

     EHCI controllers are peculiar in that they can only handle the USB 2.0
     protocol.	This means that they normally have one or more companion con-
     trollers (i.e., ohci(4) or uhci(4)) handling USB 1.x devices.  Conse-
     quently each USB connector is electrically connected to two USB con-
     trollers.	The handling of this is totally automatic, but can be noticed
     since USB 1.x and USB 2.0 devices plugged into the same connector appear
     to connect to different USB busses.

     The ehci driver is automatically loaded upon boot.  To disable this
     behavior temporarily, the ehci_load variable can be unset at the loader
     prompt (see loader(8)).  To disable it permanently, the
     hint.ehci.0.disabled tunable can be set to 1 in /boot/loader.conf.

SEE ALSO
     cardbus(4), ohci(4), pci(4), uhci(4), usb(4)

HISTORY
     The ehci driver appeared in DragonFly 1.0.

BUGS
     There is no support (yet) for interrupt or isochronous transfers.

DragonFly 3.5			 July 4, 2010			 DragonFly 3.5