1 What: /sys/bus/usb/devices/INTERFACE/authorized
4 This allows to authorize (1) or deauthorize (0)
5 individual interfaces instead a whole device
6 in contrast to the device authorization.
7 If a deauthorized interface will be authorized
8 so the driver probing must be triggered manually
9 by writing INTERFACE to /sys/bus/usb/drivers_probe
10 This allows to avoid side-effects with drivers
11 that need multiple interfaces.
13 A deauthorized interface cannot be probed or claimed.
15 What: /sys/bus/usb/devices/usbX/interface_authorized_default
18 This is used as value that determines if interfaces
19 would be authorized by default.
20 The value can be 1 or 0. It's by default 1.
22 What: /sys/bus/usb/device/.../authorized
25 Contact: David Vrabel <david.vrabel@csr.com>
27 Authorized devices are available for use by device
28 drivers, non-authorized one are not. By default, wired
29 USB devices are authorized.
31 Certified Wireless USB devices are not authorized
32 initially and should be (by writing 1) after the
33 device has been authenticated.
35 What: /sys/bus/usb/device/.../wusb_cdid
38 Contact: David Vrabel <david.vrabel@csr.com>
40 For Certified Wireless USB devices only.
42 A devices's CDID, as 16 space-separated hex octets.
44 What: /sys/bus/usb/device/.../wusb_ck
47 Contact: David Vrabel <david.vrabel@csr.com>
49 For Certified Wireless USB devices only.
51 Write the device's connection key (CK) to start the
52 authentication of the device. The CK is 16
53 space-separated hex octets.
55 What: /sys/bus/usb/device/.../wusb_disconnect
58 Contact: David Vrabel <david.vrabel@csr.com>
60 For Certified Wireless USB devices only.
62 Write a 1 to force the device to disconnect
63 (equivalent to unplugging a wired USB device).
65 What: /sys/bus/usb/drivers/.../new_id
67 Contact: linux-usb@vger.kernel.org
69 Writing a device ID to this file will attempt to
70 dynamically add a new device ID to a USB device driver.
71 This may allow the driver to support more hardware than
72 was included in the driver's static device ID support
73 table at compile time. The format for the device ID is:
74 idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct
75 The vendor ID and device ID fields are required, the
76 rest is optional. The `Ref*` tuple can be used to tell the
77 driver to use the same driver_data for the new device as
78 it is used for the reference device.
79 Upon successfully adding an ID, the driver will probe
80 for the device and attempt to bind to it. For example::
82 # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
84 Here add a new device (0458:7045) using driver_data from
85 an already supported device (0458:704c)::
87 # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id
89 Reading from this file will list all dynamically added
90 device IDs in the same format, with one entry per
93 # cat /sys/bus/usb/drivers/foo/new_id
98 The list will be truncated at PAGE_SIZE bytes due to
101 What: /sys/bus/usb-serial/drivers/.../new_id
103 Contact: linux-usb@vger.kernel.org
105 For serial USB drivers, this attribute appears under the
106 extra bus folder "usb-serial" in sysfs; apart from that
107 difference, all descriptions from the entry
108 "/sys/bus/usb/drivers/.../new_id" apply.
110 What: /sys/bus/usb/drivers/.../remove_id
112 Contact: CHENG Renquan <rqcheng@smu.edu.sg>
114 Writing a device ID to this file will remove an ID
115 that was dynamically added via the new_id sysfs entry.
116 The format for the device ID is:
117 idVendor idProduct. After successfully
118 removing an ID, the driver will no longer support the
119 device. This is useful to ensure auto probing won't
120 match the driver to the device. For example:
121 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
123 Reading from this file will list the dynamically added
124 device IDs, exactly like reading from the entry
125 "/sys/bus/usb/drivers/.../new_id"
127 What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm
129 Contact: Andiry Xu <andiry.xu@amd.com>
131 If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged
132 in to a xHCI host which support link PM, it will perform a LPM
133 test; if the test is passed and host supports USB2 hardware LPM
134 (xHCI 1.0 feature), USB2 hardware LPM will be enabled for the
135 device and the USB device directory will contain a file named
136 power/usb2_hardware_lpm. The file holds a string value (enable
137 or disable) indicating whether or not USB2 hardware LPM is
138 enabled for the device. Developer can write y/Y/1 or n/N/0 to
139 the file to enable/disable the feature.
141 What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
142 /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
144 Contact: Kevin Strasser <kevin.strasser@linux.intel.com>
145 Lu Baolu <baolu.lu@linux.intel.com>
147 If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
148 in to a xHCI host which supports link PM, it will check if U1
149 and U2 exit latencies have been set in the BOS descriptor; if
150 the check is passed and the host supports USB3 hardware LPM,
151 USB3 hardware LPM will be enabled for the device and the USB
152 device directory will contain two files named
153 power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
154 files hold a string value (enable or disable) indicating whether
155 or not USB3 hardware LPM U1 or U2 is enabled for the device.
157 What: /sys/bus/usb/devices/.../ltm_capable
159 Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com>
161 USB 3.0 devices may optionally support Latency Tolerance
162 Messaging (LTM). They indicate their support by setting a bit
163 in the bmAttributes field of their SuperSpeed BOS descriptors.
164 If that bit is set for the device, ltm_capable will read "yes".
165 If the device doesn't support LTM, the file will read "no".
166 The file will be present for all speeds of USB devices, and will
167 always read "no" for USB 1.1 and USB 2.0 devices.
169 What: /sys/bus/usb/devices/.../(hub interface)/portX
171 Contact: Lan Tianyu <tianyu.lan@intel.com>
173 The /sys/bus/usb/devices/.../(hub interface)/portX
174 is usb port device's sysfs directory.
176 What: /sys/bus/usb/devices/.../(hub interface)/portX/connect_type
178 Contact: Lan Tianyu <tianyu.lan@intel.com>
180 Some platforms provide usb port connect types through ACPI.
181 This attribute is to expose these information to user space.
182 The file will read "hotplug", "hardwired" and "not used" if the
183 information is available, and "unknown" otherwise.
185 What: /sys/bus/usb/devices/.../(hub interface)/portX/location
187 Contact: Bjørn Mork <bjorn@mork.no>
189 Some platforms provide usb port physical location through
190 firmware. This is used by the kernel to pair up logical ports
191 mapping to the same physical connector. The attribute exposes the
192 raw location value as a hex integer.
195 What: /sys/bus/usb/devices/.../(hub interface)/portX/quirks
197 Contact: Nicolas Boichat <drinkcat@chromium.org>
199 In some cases, we care about time-to-active for devices
200 connected on a specific port (e.g. non-standard USB port like
201 pogo pins), where the device to be connected is known in
202 advance, and behaves well according to the specification.
203 This attribute is a bit-field that controls the behavior of
206 - Bit 0 of this field selects the "old" enumeration scheme,
207 as it is considerably faster (it only causes one USB reset
210 The old enumeration scheme can also be selected globally
211 using /sys/module/usbcore/parameters/old_scheme_first, but
212 it is often not desirable as the new scheme was introduced to
213 increase compatibility with more devices.
214 - Bit 1 reduces TRSTRCY to the 10 ms that are required by the
215 USB 2.0 specification, instead of the 50 ms that are normally
216 used to help make enumeration work better on some high speed
219 What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count
221 Contact: Richard Leitner <richard.leitner@skidata.com>
223 Most hubs are able to detect over-current situations on their
224 ports and report them to the kernel. This attribute is to expose
225 the number of over-current situation occurred on a specific port
226 to user space. This file will contain an unsigned 32 bit value
227 which wraps to 0 after its maximum is reached. This file supports
228 poll() for monitoring changes to this value in user space.
230 Any time this value changes the corresponding hub device will send a
231 udev event with the following attributes::
233 OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX
234 OVER_CURRENT_COUNT=[current value of this sysfs attribute]
236 What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
238 Contact: Lu Baolu <baolu.lu@linux.intel.com>
240 Some USB3.0 devices are not friendly to USB3 LPM. usb3_lpm_permit
241 attribute allows enabling/disabling usb3 lpm of a port. It takes
242 effect both before and after a usb device is enumerated. Supported
243 values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1
244 is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and
247 What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
249 Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
251 USB 2.0 devices may support hardware link power management (LPM)
252 L1 sleep state. The usb2_lpm_l1_timeout attribute allows
253 tuning the timeout for L1 inactivity timer (LPM timer), e.g.
254 needed inactivity time before host requests the device to go to L1 sleep.
255 Useful for power management tuning.
256 Supported values are 0 - 65535 microseconds.
258 What: /sys/bus/usb/devices/.../power/usb2_lpm_besl
260 Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
262 USB 2.0 devices that support hardware link power management (LPM)
263 L1 sleep state now use a best effort service latency value (BESL) to
264 indicate the best effort to resumption of service to the device after the
265 initiation of the resume event.
266 If the device does not have a preferred besl value then the host can select
267 one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
268 value in order to tune power saving and service latency.
270 Supported values are 0 - 15.
271 More information on how besl values map to microseconds can be found in
272 USB 2.0 ECN Errata for Link Power Management, section 4.10)
274 What: /sys/bus/usb/devices/.../rx_lanes
276 Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
278 Number of rx lanes the device is using.
279 USB 3.2 adds Dual-lane support, 2 rx and 2 tx lanes over Type-C.
280 Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per
281 direction. Devices before USB 3.2 are single lane (rx_lanes = 1)
283 What: /sys/bus/usb/devices/.../tx_lanes
285 Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
287 Number of tx lanes the device is using.
288 USB 3.2 adds Dual-lane support, 2 rx and 2 tx -lanes over Type-C.
289 Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per
290 direction. Devices before USB 3.2 are single lane (tx_lanes = 1)