FreeBSD Manual Pages
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 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., ohci(4) or uhci(4)) handling USB 1.x devices. Con- sequently each USB connector is electrically connected to two USB con- trollers. The handling of this is totally automatic, but can be no- ticed since USB 1.x and USB 2.0 devices plugged in to the same connec- tor appear to connect to different USB buses. LOADER TUNABLES When the kernel has been compiled with options USB_DEBUG, some tunables become available that affect the behavior of ehci. These tunables can be set at the loader(8) prompt before booting the kernel or stored in loader.conf(5). hw.usb.ehci.lostintrbug This tunable enables the lost interrupt quirk. The default value is 0 (off). hw.usb.ehci.iaadbug This tunable enables the EHCI doorbell quirk. The default value is 0 (off). 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). SYSCTL VARIABLES The following variables are available as both sysctl(8) variables and loader(8) tunables: hw.usb.ehci.debug Debug output level, where 0 is debugging disabled and larger values increase debug message verbosity. Default is 0. SEE ALSO ohci(4), uhci(4), usb(4), xhci(4) HISTORY The ehci device driver first appeared in FreeBSD 5.1. FreeBSD 14.3 April 24, 2018 EHCI(4)
NAME | SYNOPSIS | DESCRIPTION | LOADER TUNABLES | SYSCTL VARIABLES | SEE ALSO | HISTORY
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