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1What: /sys/bus/usb/devices/.../power/autosuspend
2Date: March 2007
3KernelVersion: 2.6.21
4Contact: Alan Stern <stern@rowland.harvard.edu>
5Description:
6 Each USB device directory will contain a file named
7 power/autosuspend. This file holds the time (in seconds)
8 the device must be idle before it will be autosuspended.
9 0 means the device will be autosuspended as soon as
10 possible. Negative values will prevent the device from
11 being autosuspended at all, and writing a negative value
12 will resume the device if it is already suspended.
13
14 The autosuspend delay for newly-created devices is set to
15 the value of the usbcore.autosuspend module parameter.
16
17What: /sys/bus/usb/devices/.../power/persist
18Date: May 2007
19KernelVersion: 2.6.23
20Contact: Alan Stern <stern@rowland.harvard.edu>
21Description:
22 If CONFIG_USB_PERSIST is set, then each USB device directory
23 will contain a file named power/persist. The file holds a
24 boolean value (0 or 1) indicating whether or not the
25 "USB-Persist" facility is enabled for the device. Since the
26 facility is inherently dangerous, it is disabled by default
27 for all devices except hubs. For more information, see
28 Documentation/usb/persist.txt.
29
30What: /sys/bus/usb/device/.../power/connected_duration
31Date: January 2008
32KernelVersion: 2.6.25
33Contact: Sarah Sharp <sarah.a.sharp@intel.com>
34Description:
35 If CONFIG_PM and CONFIG_USB_SUSPEND are 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.
39Users:
40 PowerTOP <power@bughost.org>
41 http://www.lesswatts.org/projects/powertop/
42
43What: /sys/bus/usb/device/.../power/active_duration
44Date: January 2008
45KernelVersion: 2.6.25
46Contact: Sarah Sharp <sarah.a.sharp@intel.com>
47Description:
48 If CONFIG_PM and CONFIG_USB_SUSPEND are 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.
59Users:
60 PowerTOP <power@bughost.org>
61 http://www.lesswatts.org/projects/powertop/
62
63What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend
64Date: January 2008
65KernelVersion: 2.6.27
66Contact: Sarah Sharp <sarah.a.sharp@intel.com>
67Description:
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.
75Users:
76 USB PM tool
77 git://git.moblin.org/users/sarah/usb-pm-tool/
78
79What: /sys/bus/usb/device/.../authorized
80Date: July 2008
81KernelVersion: 2.6.26
82Contact: David Vrabel <david.vrabel@csr.com>
83Description:
84 Authorized devices are available for use by device
85 drivers, non-authorized one are not. By default, wired
86 USB devices are authorized.
87
88 Certified Wireless USB devices are not authorized
89 initially and should be (by writing 1) after the
90 device has been authenticated.
91
92What: /sys/bus/usb/device/.../wusb_cdid
93Date: July 2008
94KernelVersion: 2.6.27
95Contact: David Vrabel <david.vrabel@csr.com>
96Description:
97 For Certified Wireless USB devices only.
98
99 A devices's CDID, as 16 space-separated hex octets.
100
101What: /sys/bus/usb/device/.../wusb_ck
102Date: July 2008
103KernelVersion: 2.6.27
104Contact: David Vrabel <david.vrabel@csr.com>
105Description:
106 For Certified Wireless USB devices only.
107
108 Write the device's connection key (CK) to start the
109 authentication of the device. The CK is 16
110 space-separated hex octets.
111
112What: /sys/bus/usb/device/.../wusb_disconnect
113Date: July 2008
114KernelVersion: 2.6.27
115Contact: David Vrabel <david.vrabel@csr.com>
116Description:
117 For Certified Wireless USB devices only.
118
119 Write a 1 to force the device to disconnect
120 (equivalent to unplugging a wired USB device).
121
122What: /sys/bus/usb/drivers/.../remove_id
123Date: November 2009
124Contact: CHENG Renquan <rqcheng@smu.edu.sg>
125Description:
126 Writing a device ID to this file will remove an ID
127 that was dynamically added via the new_id sysfs entry.
128 The format for the device ID is:
129 idVendor idProduct. After successfully
130 removing an ID, the driver will no longer support the
131 device. This is useful to ensure auto probing won't
132 match the driver to the device. For example:
133 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
134
135What: /sys/bus/usb/device/.../avoid_reset_quirk
136Date: December 2009
137Contact: Oliver Neukum <oliver@neukum.org>
138Description:
139 Writing 1 to this file tells the kernel that this
140 device will morph into another mode when it is reset.
141 Drivers will not use reset for error handling for
142 such devices.
143Users:
144 usb_modeswitch
1What: /sys/bus/usb/device/.../authorized
2Date: July 2008
3KernelVersion: 2.6.26
4Contact: David Vrabel <david.vrabel@csr.com>
5Description:
6 Authorized devices are available for use by device
7 drivers, non-authorized one are not. By default, wired
8 USB devices are authorized.
9
10 Certified Wireless USB devices are not authorized
11 initially and should be (by writing 1) after the
12 device has been authenticated.
13
14What: /sys/bus/usb/device/.../wusb_cdid
15Date: July 2008
16KernelVersion: 2.6.27
17Contact: David Vrabel <david.vrabel@csr.com>
18Description:
19 For Certified Wireless USB devices only.
20
21 A devices's CDID, as 16 space-separated hex octets.
22
23What: /sys/bus/usb/device/.../wusb_ck
24Date: July 2008
25KernelVersion: 2.6.27
26Contact: David Vrabel <david.vrabel@csr.com>
27Description:
28 For Certified Wireless USB devices only.
29
30 Write the device's connection key (CK) to start the
31 authentication of the device. The CK is 16
32 space-separated hex octets.
33
34What: /sys/bus/usb/device/.../wusb_disconnect
35Date: July 2008
36KernelVersion: 2.6.27
37Contact: David Vrabel <david.vrabel@csr.com>
38Description:
39 For Certified Wireless USB devices only.
40
41 Write a 1 to force the device to disconnect
42 (equivalent to unplugging a wired USB device).
43
44What: /sys/bus/usb/drivers/.../new_id
45Date: October 2011
46Contact: linux-usb@vger.kernel.org
47Description:
48 Writing a device ID to this file will attempt to
49 dynamically add a new device ID to a USB device driver.
50 This may allow the driver to support more hardware than
51 was included in the driver's static device ID support
52 table at compile time. The format for the device ID is:
53 idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct
54 The vendor ID and device ID fields are required, the
55 rest is optional. The Ref* tuple can be used to tell the
56 driver to use the same driver_data for the new device as
57 it is used for the reference device.
58 Upon successfully adding an ID, the driver will probe
59 for the device and attempt to bind to it. For example:
60 # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
61
62 Here add a new device (0458:7045) using driver_data from
63 an already supported device (0458:704c):
64 # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id
65
66 Reading from this file will list all dynamically added
67 device IDs in the same format, with one entry per
68 line. For example:
69 # cat /sys/bus/usb/drivers/foo/new_id
70 8086 10f5
71 dead beef 06
72 f00d cafe
73
74 The list will be truncated at PAGE_SIZE bytes due to
75 sysfs restrictions.
76
77What: /sys/bus/usb-serial/drivers/.../new_id
78Date: October 2011
79Contact: linux-usb@vger.kernel.org
80Description:
81 For serial USB drivers, this attribute appears under the
82 extra bus folder "usb-serial" in sysfs; apart from that
83 difference, all descriptions from the entry
84 "/sys/bus/usb/drivers/.../new_id" apply.
85
86What: /sys/bus/usb/drivers/.../remove_id
87Date: November 2009
88Contact: CHENG Renquan <rqcheng@smu.edu.sg>
89Description:
90 Writing a device ID to this file will remove an ID
91 that was dynamically added via the new_id sysfs entry.
92 The format for the device ID is:
93 idVendor idProduct. After successfully
94 removing an ID, the driver will no longer support the
95 device. This is useful to ensure auto probing won't
96 match the driver to the device. For example:
97 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
98
99 Reading from this file will list the dynamically added
100 device IDs, exactly like reading from the entry
101 "/sys/bus/usb/drivers/.../new_id"
102
103What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm
104Date: September 2011
105Contact: Andiry Xu <andiry.xu@amd.com>
106Description:
107 If CONFIG_PM_RUNTIME is set and a USB 2.0 lpm-capable device
108 is plugged in to a xHCI host which support link PM, it will
109 perform a LPM test; if the test is passed and host supports
110 USB2 hardware LPM (xHCI 1.0 feature), USB2 hardware LPM will
111 be enabled for the device and the USB device directory will
112 contain a file named power/usb2_hardware_lpm. The file holds
113 a string value (enable or disable) indicating whether or not
114 USB2 hardware LPM is enabled for the device. Developer can
115 write y/Y/1 or n/N/0 to the file to enable/disable the
116 feature.
117
118What: /sys/bus/usb/devices/.../removable
119Date: February 2012
120Contact: Matthew Garrett <mjg@redhat.com>
121Description:
122 Some information about whether a given USB device is
123 physically fixed to the platform can be inferred from a
124 combination of hub descriptor bits and platform-specific data
125 such as ACPI. This file will read either "removable" or
126 "fixed" if the information is available, and "unknown"
127 otherwise.
128
129What: /sys/bus/usb/devices/.../ltm_capable
130Date: July 2012
131Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com>
132Description:
133 USB 3.0 devices may optionally support Latency Tolerance
134 Messaging (LTM). They indicate their support by setting a bit
135 in the bmAttributes field of their SuperSpeed BOS descriptors.
136 If that bit is set for the device, ltm_capable will read "yes".
137 If the device doesn't support LTM, the file will read "no".
138 The file will be present for all speeds of USB devices, and will
139 always read "no" for USB 1.1 and USB 2.0 devices.
140
141What: /sys/bus/usb/devices/.../(hub interface)/portX
142Date: August 2012
143Contact: Lan Tianyu <tianyu.lan@intel.com>
144Description:
145 The /sys/bus/usb/devices/.../(hub interface)/portX
146 is usb port device's sysfs directory.
147
148What: /sys/bus/usb/devices/.../(hub interface)/portX/connect_type
149Date: January 2013
150Contact: Lan Tianyu <tianyu.lan@intel.com>
151Description:
152 Some platforms provide usb port connect types through ACPI.
153 This attribute is to expose these information to user space.
154 The file will read "hotplug", "wired" and "not used" if the
155 information is available, and "unknown" otherwise.
156
157What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
158Date: May 2013
159Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
160Description:
161 USB 2.0 devices may support hardware link power management (LPM)
162 L1 sleep state. The usb2_lpm_l1_timeout attribute allows
163 tuning the timeout for L1 inactivity timer (LPM timer), e.g.
164 needed inactivity time before host requests the device to go to L1 sleep.
165 Useful for power management tuning.
166 Supported values are 0 - 65535 microseconds.
167
168What: /sys/bus/usb/devices/.../power/usb2_lpm_besl
169Date: May 2013
170Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
171Description:
172 USB 2.0 devices that support hardware link power management (LPM)
173 L1 sleep state now use a best effort service latency value (BESL) to
174 indicate the best effort to resumption of service to the device after the
175 initiation of the resume event.
176 If the device does not have a preferred besl value then the host can select
177 one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
178 value in order to tune power saving and service latency.
179
180 Supported values are 0 - 15.
181 More information on how besl values map to microseconds can be found in
182 USB 2.0 ECN Errata for Link Power Management, section 4.10)