Link Layer Validation Device is a standard device for testing of Super
Speed Link Layer tests. These nodes are available in sysfs only when lvs
driver is bound with root hub device.

What:		/sys/bus/usb/devices/.../get_dev_desc
Date:		March 2014
Contact:	Pratyush Anand <pratyush.anand@gmail.com>
Description:
		Write to this node to issue "Get Device Descriptor"
		for Link Layer Validation device. It is needed for TD.7.06.

What:		/sys/bus/usb/devices/.../u1_timeout
Date:		March 2014
Contact:	Pratyush Anand <pratyush.anand@gmail.com>
Description:
		Set "U1 timeout" for the downstream port where Link Layer
		Validation device is connected. Timeout value must be between 0
		and 127. It is needed for TD.7.18, TD.7.19, TD.7.20 and TD.7.21.

What:		/sys/bus/usb/devices/.../u2_timeout
Date:		March 2014
Contact:	Pratyush Anand <pratyush.anand@gmail.com>
Description:
		Set "U2 timeout" for the downstream port where Link Layer
		Validation device is connected. Timeout value must be between 0
		and 127. It is needed for TD.7.18, TD.7.19, TD.7.20 and TD.7.21.

What:		/sys/bus/usb/devices/.../hot_reset
Date:		March 2014
Contact:	Pratyush Anand <pratyush.anand@gmail.com>
Description:
		Write to this node to issue "Reset" for Link Layer Validation
		device. It is needed for TD.7.29, TD.7.31, TD.7.34 and TD.7.35.

What:		/sys/bus/usb/devices/.../u3_entry
Date:		March 2014
Contact:	Pratyush Anand <pratyush.anand@gmail.com>
Description:
		Write to this node to issue "U3 entry" for Link Layer
		Validation device. It is needed for TD.7.35 and TD.7.36.

What:		/sys/bus/usb/devices/.../u3_exit
Date:		March 2014
Contact:	Pratyush Anand <pratyush.anand@gmail.com>
Description:
		Write to this node to issue "U3 exit" for Link Layer
		Validation device. It is needed for TD.7.36.

What:		/sys/bus/usb/devices/.../enable_compliance
Date:		July 2017
Description:
		Write to this node to set the port to compliance mode to test
		with Link Layer Validation device. It is needed for TD.7.34.

What:		/sys/bus/usb/devices/.../warm_reset
Date:		July 2017
Description:
		Write to this node to issue "Warm Reset" for Link Layer Validation
		device. It may be needed to properly reset an xHCI 1.1 host port if
		compliance mode needed to be explicitly enabled.