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Based on kernel version 4.1. Page generated on 2015-06-28 12:07 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			USB device directories can contain a file named power/persist.
7			The file holds a boolean value (0 or 1) indicating whether or
8			not the "USB-Persist" facility is enabled for the device.  For
9			hubs this facility is always enabled and their device
10			directories will not contain this file.
11	
12			For more information, see 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 is enabled, then this file is present.  When read,
36			it returns the total time (in msec) that the USB device has been
37			connected to the machine.  This file is read-only.
38	Users:
39			PowerTOP <powertop@lists.01.org>
40			https://01.org/powertop/
41	
42	What:		/sys/bus/usb/device/.../power/active_duration
43	Date:		January 2008
44	KernelVersion:	2.6.25
45	Contact:	Sarah Sharp <sarah.a.sharp@intel.com>
46	Description:
47			If CONFIG_PM is enabled, then this file is present.  When read,
48			it returns the total time (in msec) that the USB device has been
49			active, i.e. not in a suspended state.  This file is read-only.
50	
51			Tools can use this file and the connected_duration file to
52			compute the percentage of time that a device has been active.
53			For example,
54			echo $((100 * `cat active_duration` / `cat connected_duration`))
55			will give an integer percentage.  Note that this does not
56			account for counter wrap.
57	Users:
58			PowerTOP <powertop@lists.01.org>
59			https://01.org/powertop/
60	
61	What:		/sys/bus/usb/devices/<busnum>-<port[.port]>...:<config num>-<interface num>/supports_autosuspend
62	Date:		January 2008
63	KernelVersion:	2.6.27
64	Contact:	Sarah Sharp <sarah.a.sharp@intel.com>
65	Description:
66			When read, this file returns 1 if the interface driver
67			for this interface supports autosuspend.  It also
68			returns 1 if no driver has claimed this interface, as an
69			unclaimed interface will not stop the device from being
70			autosuspended if all other interface drivers are idle.
71			The file returns 0 if autosuspend support has not been
72			added to the driver.
73	Users:
74			USB PM tool
75			git://git.moblin.org/users/sarah/usb-pm-tool/
76	
77	What:		/sys/bus/usb/device/.../avoid_reset_quirk
78	Date:		December 2009
79	Contact:	Oliver Neukum <oliver@neukum.org>
80	Description:
81			Writing 1 to this file tells the kernel that this
82			device will morph into another mode when it is reset.
83			Drivers will not use reset for error handling for
84			such devices.
85	Users:
86			usb_modeswitch
87	
88	What:		/sys/bus/usb/devices/.../devnum
89	KernelVersion:	since at least 2.6.18
90	Description:
91			Device address on the USB bus.
92	Users:
93			libusb
94	
95	What:		/sys/bus/usb/devices/.../bConfigurationValue
96	KernelVersion:	since at least 2.6.18
97	Description:
98			bConfigurationValue of the *active* configuration for the
99			device. Writing 0 or -1 to bConfigurationValue will reset the
100			active configuration (unconfigure the device). Writing
101			another value will change the active configuration.
102	
103			Note that some devices, in violation of the USB spec, have a
104			configuration with a value equal to 0. Writing 0 to
105			bConfigurationValue for these devices will install that
106			configuration, rather then unconfigure the device.
107	
108			Writing -1 will always unconfigure the device.
109	Users:
110			libusb
111	
112	What:		/sys/bus/usb/devices/.../busnum
113	KernelVersion:	2.6.22
114	Description:
115			Bus-number of the USB-bus the device is connected to.
116	Users:
117			libusb
118	
119	What:		/sys/bus/usb/devices/.../descriptors
120	KernelVersion:	2.6.26
121	Description:
122			Binary file containing cached descriptors of the device. The
123			binary data consists of the device descriptor followed by the
124			descriptors for each configuration of the device.
125			Note that the wTotalLength of the config descriptors can not
126			be trusted, as the device may have a smaller config descriptor
127			than it advertises. The bLength field of each (sub) descriptor
128			can be trusted, and can be used to seek forward one (sub)
129			descriptor at a time until the next config descriptor is found.
130			All descriptors read from this file are in bus-endian format
131	Users:
132			libusb
133	
134	What:		/sys/bus/usb/devices/.../speed
135	KernelVersion:	since at least 2.6.18
136	Description:
137			Speed the device is connected with to the usb-host in
138			Mbit / second. IE one of 1.5 / 12 / 480 / 5000.
139	Users:
140			libusb
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