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