USB Enhanced Host Controller driver
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 controllers (i.e.,
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 different USB busses.
device driver first appeared in
When the kernel has been compiled with
, some tunables become available that affect the behavior of
. These tunables can be set at the
prompt before booting the kernel or
stored in loader.conf(5)
- This tunable enables the lost interrupt quirk. The default value is 0
- This tunable enables the EHCI doorbell quirk. The default value is 0
- 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).