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Based on kernel version 3.15.4. Page generated on 2014-07-07 08:59 EST.

1	What:		/sys/bus/usb/devices/.../power/persist
2	Date:		May 2007
3	KernelVersion:	2.6.23
4	Contact:	Alan Stern <stern@rowland.harvard.edu>
5	Description:
6			If CONFIG_USB_PERSIST is set, then each USB device directory
7			will contain a file named power/persist.  The file holds a
8			boolean value (0 or 1) indicating whether or not the
9			"USB-Persist" facility is enabled for the device.  Since the
10			facility is inherently dangerous, it is disabled by default
11			for all devices except hubs.  For more information, see
12			Documentation/usb/persist.txt.
13	
14	What:		/sys/bus/usb/devices/.../power/autosuspend
15	Date:		March 2007
16	KernelVersion:	2.6.21
17	Contact:	Alan Stern <stern@rowland.harvard.edu>
18	Description:
19			Each USB device directory will contain a file named
20			power/autosuspend.  This file holds the time (in seconds)
21			the device must be idle before it will be autosuspended.
22			0 means the device will be autosuspended as soon as
23			possible.  Negative values will prevent the device from
24			being autosuspended at all, and writing a negative value
25			will resume the device if it is already suspended.
26	
27			The autosuspend delay for newly-created devices is set to
28			the value of the usbcore.autosuspend module parameter.
29	
30	What:		/sys/bus/usb/device/.../power/connected_duration
31	Date:		January 2008
32	KernelVersion:	2.6.25
33	Contact:	Sarah Sharp <sarah.a.sharp@intel.com>
34	Description:
35			If CONFIG_PM_RUNTIME is enabled then this file
36			is present.  When read, it returns the total time (in msec)
37			that the USB device has been connected to the machine.  This
38			file is read-only.
39	Users:
40			PowerTOP <powertop@lists.01.org>
41			https://01.org/powertop/
42	
43	What:		/sys/bus/usb/device/.../power/active_duration
44	Date:		January 2008
45	KernelVersion:	2.6.25
46	Contact:	Sarah Sharp <sarah.a.sharp@intel.com>
47	Description:
48			If CONFIG_PM_RUNTIME is enabled then this file
49			is present.  When read, it returns the total time (in msec)
50			that the USB device has been active, i.e. not in a suspended
51			state.  This file is read-only.
52	
53			Tools can use this file and the connected_duration file to
54			compute the percentage of time that a device has been active.
55			For example,
56			echo $((100 * `cat active_duration` / `cat connected_duration`))
57			will give an integer percentage.  Note that this does not
58			account for counter wrap.
59	Users:
60			PowerTOP <powertop@lists.01.org>
61			https://01.org/powertop/
62	
63	What:		/sys/bus/usb/devices/<busnum>-<port[.port]>...:<config num>-<interface num>/supports_autosuspend
64	Date:		January 2008
65	KernelVersion:	2.6.27
66	Contact:	Sarah Sharp <sarah.a.sharp@intel.com>
67	Description:
68			When read, this file returns 1 if the interface driver
69			for this interface supports autosuspend.  It also
70			returns 1 if no driver has claimed this interface, as an
71			unclaimed interface will not stop the device from being
72			autosuspended if all other interface drivers are idle.
73			The file returns 0 if autosuspend support has not been
74			added to the driver.
75	Users:
76			USB PM tool
77			git://git.moblin.org/users/sarah/usb-pm-tool/
78	
79	What:		/sys/bus/usb/device/.../avoid_reset_quirk
80	Date:		December 2009
81	Contact:	Oliver Neukum <oliver@neukum.org>
82	Description:
83			Writing 1 to this file tells the kernel that this
84			device will morph into another mode when it is reset.
85			Drivers will not use reset for error handling for
86			such devices.
87	Users:
88			usb_modeswitch
89	
90	What:		/sys/bus/usb/devices/.../devnum
91	KernelVersion:	since at least 2.6.18
92	Description:
93			Device address on the USB bus.
94	Users:
95			libusb
96	
97	What:		/sys/bus/usb/devices/.../bConfigurationValue
98	KernelVersion:	since at least 2.6.18
99	Description:
100			bConfigurationValue of the *active* configuration for the
101			device. Writing 0 or -1 to bConfigurationValue will reset the
102			active configuration (unconfigure the device). Writing
103			another value will change the active configuration.
104	
105			Note that some devices, in violation of the USB spec, have a
106			configuration with a value equal to 0. Writing 0 to
107			bConfigurationValue for these devices will install that
108			configuration, rather then unconfigure the device.
109	
110			Writing -1 will always unconfigure the device.
111	Users:
112			libusb
113	
114	What:		/sys/bus/usb/devices/.../busnum
115	KernelVersion:	2.6.22
116	Description:
117			Bus-number of the USB-bus the device is connected to.
118	Users:
119			libusb
120	
121	What:		/sys/bus/usb/devices/.../descriptors
122	KernelVersion:	2.6.26
123	Description:
124			Binary file containing cached descriptors of the device. The
125			binary data consists of the device descriptor followed by the
126			descriptors for each configuration of the device.
127			Note that the wTotalLength of the config descriptors can not
128			be trusted, as the device may have a smaller config descriptor
129			than it advertises. The bLength field of each (sub) descriptor
130			can be trusted, and can be used to seek forward one (sub)
131			descriptor at a time until the next config descriptor is found.
132			All descriptors read from this file are in bus-endian format
133	Users:
134			libusb
135	
136	What:		/sys/bus/usb/devices/.../speed
137	KernelVersion:	since at least 2.6.18
138	Description:
139			Speed the device is connected with to the usb-host in
140			Mbit / second. IE one of 1.5 / 12 / 480 / 5000.
141	Users:
142			libusb
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