Documentation sysfs-bus-usb: Document all files used by libusb

		Supported values are 0 - 15.

		More information on how besl values map to microseconds can be found in

		USB 2.0 ECN Errata for Link Power Management, section 4.10)

What:		/sys/bus/usb/devices/.../devnum

KernelVersion:	since at least 2.6.18

Description:

		Device address on the USB bus.

What:		/sys/bus/usb/devices/.../bConfigurationValue

KernelVersion:	since at least 2.6.18

Description:

		bConfigurationValue of the *active* configuration for the

		device. Writing 0 or -1 to bConfigurationValue will reset the

		active configuration (unconfigure the device). Writing

		another value will change the active configuration.

		Note that some devices, in violation of the USB spec, have a

		configuration with a value equal to 0. Writing 0 to

		bConfigurationValue for these devices will install that

		configuration, rather then unconfigure the device.

		Writing -1 will always unconfigure the device.

What:		/sys/bus/usb/devices/.../busnum

KernelVersion:	2.6.22

Description:

		Bus-number of the USB-bus the device is connected to.

What:		/sys/bus/usb/devices/.../descriptors

KernelVersion:	2.6.26

Description:

		Binary file containing cached descriptors of the device. The

		binary data consists of the device descriptor followed by the

		descriptors for each configuration of the device.

		Note that the wTotalLength of the config descriptors can not

		be trusted, as the device may have a smaller config descriptor

		than it advertises. The bLength field of each (sub) descriptor

		can be trusted, and can be used to seek forward one (sub)

		descriptor at a time until the next config descriptor is found.

		All descriptors read from this file are in bus-endian format