1What: /sys/bus/usb/devices/INTERFACE/authorized 2Date: August 2015 3Description: 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. 12 13 A deauthorized interface cannot be probed or claimed. 14 15What: /sys/bus/usb/devices/usbX/interface_authorized_default 16Date: August 2015 17Description: 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. 21 22What: /sys/bus/usb/device/.../authorized 23Date: July 2008 24KernelVersion: 2.6.26 25Contact: David Vrabel <david.vrabel@csr.com> 26Description: 27 Authorized devices are available for use by device 28 drivers, non-authorized one are not. By default, wired 29 USB devices are authorized. 30 31 Certified Wireless USB devices are not authorized 32 initially and should be (by writing 1) after the 33 device has been authenticated. 34 35What: /sys/bus/usb/device/.../wusb_cdid 36Date: July 2008 37KernelVersion: 2.6.27 38Contact: David Vrabel <david.vrabel@csr.com> 39Description: 40 For Certified Wireless USB devices only. 41 42 A devices's CDID, as 16 space-separated hex octets. 43 44What: /sys/bus/usb/device/.../wusb_ck 45Date: July 2008 46KernelVersion: 2.6.27 47Contact: David Vrabel <david.vrabel@csr.com> 48Description: 49 For Certified Wireless USB devices only. 50 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. 54 55What: /sys/bus/usb/device/.../wusb_disconnect 56Date: July 2008 57KernelVersion: 2.6.27 58Contact: David Vrabel <david.vrabel@csr.com> 59Description: 60 For Certified Wireless USB devices only. 61 62 Write a 1 to force the device to disconnect 63 (equivalent to unplugging a wired USB device). 64 65What: /sys/bus/usb/drivers/.../new_id 66Date: October 2011 67Contact: linux-usb@vger.kernel.org 68Description: 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:: 81 82 # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id 83 84 Here add a new device (0458:7045) using driver_data from 85 an already supported device (0458:704c):: 86 87 # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id 88 89 Reading from this file will list all dynamically added 90 device IDs in the same format, with one entry per 91 line. For example:: 92 93 # cat /sys/bus/usb/drivers/foo/new_id 94 8086 10f5 95 dead beef 06 96 f00d cafe 97 98 The list will be truncated at PAGE_SIZE bytes due to 99 sysfs restrictions. 100 101What: /sys/bus/usb-serial/drivers/.../new_id 102Date: October 2011 103Contact: linux-usb@vger.kernel.org 104Description: 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. 109 110What: /sys/bus/usb/drivers/.../remove_id 111Date: November 2009 112Contact: CHENG Renquan <rqcheng@smu.edu.sg> 113Description: 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 122 123 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" 126 127What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm 128Date: September 2011 129Contact: Andiry Xu <andiry.xu@amd.com> 130Description: 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. 140 141What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1 142 /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2 143Date: November 2015 144Contact: Kevin Strasser <kevin.strasser@linux.intel.com> 145 Lu Baolu <baolu.lu@linux.intel.com> 146Description: 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. 156 157What: /sys/bus/usb/devices/.../ltm_capable 158Date: July 2012 159Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com> 160Description: 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. 168 169What: /sys/bus/usb/devices/.../(hub interface)/portX 170Date: August 2012 171Contact: Lan Tianyu <tianyu.lan@intel.com> 172Description: 173 The /sys/bus/usb/devices/.../(hub interface)/portX 174 is usb port device's sysfs directory. 175 176What: /sys/bus/usb/devices/.../(hub interface)/portX/connect_type 177Date: January 2013 178Contact: Lan Tianyu <tianyu.lan@intel.com> 179Description: 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. 184 185What: /sys/bus/usb/devices/.../(hub interface)/portX/location 186Date: October 2018 187Contact: Bjørn Mork <bjorn@mork.no> 188Description: 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. 193 194 195What: /sys/bus/usb/devices/.../(hub interface)/portX/quirks 196Date: May 2018 197Contact: Nicolas Boichat <drinkcat@chromium.org> 198Description: 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 204 a specific port: 205 206 - Bit 0 of this field selects the "old" enumeration scheme, 207 as it is considerably faster (it only causes one USB reset 208 instead of 2). 209 210 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 217 devices. 218 219What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count 220Date: February 2018 221Contact: Richard Leitner <richard.leitner@skidata.com> 222Description: 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. 229 230 Any time this value changes the corresponding hub device will send a 231 udev event with the following attributes:: 232 233 OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX 234 OVER_CURRENT_COUNT=[current value of this sysfs attribute] 235 236What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit 237Date: November 2015 238Contact: Lu Baolu <baolu.lu@linux.intel.com> 239Description: 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 245 u2 are permitted. 246 247What: /sys/bus/usb/devices/.../<hub_interface>/port<X>/early_stop 248Date: Sep 2022 249Contact: Ray Chi <raychi@google.com> 250Description: 251 Some USB hosts have some watchdog mechanisms so that the device 252 may enter ramdump if it takes a long time during port initialization. 253 This attribute allows each port just has two attempts so that the 254 port initialization will be failed quickly. In addition, if a port 255 which is marked with early_stop has failed to initialize, it will ignore 256 all future connections until this attribute is clear. 257 258What: /sys/bus/usb/devices/.../<hub_interface>/port<X>/state 259Date: June 2023 260Contact: Roy Luo <royluo@google.com> 261Description: 262 Indicates current state of the USB device attached to the port. 263 Valid states are: 'not-attached', 'attached', 'powered', 264 'reconnecting', 'unauthenticated', 'default', 'addressed', 265 'configured', and 'suspended'. This file supports poll() to 266 monitor the state change from user space. 267 268What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout 269Date: May 2013 270Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 271Description: 272 USB 2.0 devices may support hardware link power management (LPM) 273 L1 sleep state. The usb2_lpm_l1_timeout attribute allows 274 tuning the timeout for L1 inactivity timer (LPM timer), e.g. 275 needed inactivity time before host requests the device to go to L1 sleep. 276 Useful for power management tuning. 277 Supported values are 0 - 65535 microseconds. 278 279What: /sys/bus/usb/devices/.../power/usb2_lpm_besl 280Date: May 2013 281Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 282Description: 283 USB 2.0 devices that support hardware link power management (LPM) 284 L1 sleep state now use a best effort service latency value (BESL) to 285 indicate the best effort to resumption of service to the device after the 286 initiation of the resume event. 287 If the device does not have a preferred besl value then the host can select 288 one instead. This usb2_lpm_besl attribute allows to tune the host selected besl 289 value in order to tune power saving and service latency. 290 291 Supported values are 0 - 15. 292 More information on how besl values map to microseconds can be found in 293 USB 2.0 ECN Errata for Link Power Management, section 4.10) 294 295What: /sys/bus/usb/devices/.../rx_lanes 296Date: March 2018 297Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 298Description: 299 Number of rx lanes the device is using. 300 USB 3.2 adds Dual-lane support, 2 rx and 2 tx lanes over Type-C. 301 Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per 302 direction. Devices before USB 3.2 are single lane (rx_lanes = 1) 303 304What: /sys/bus/usb/devices/.../tx_lanes 305Date: March 2018 306Contact: Mathias Nyman <mathias.nyman@linux.intel.com> 307Description: 308 Number of tx lanes the device is using. 309 USB 3.2 adds Dual-lane support, 2 rx and 2 tx -lanes over Type-C. 310 Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per 311 direction. Devices before USB 3.2 are single lane (tx_lanes = 1) 312