What: /sys/bus/usb/devices/INTERFACE/authorized Date: August 2015 Description: This allows to authorize (1) or deauthorize (0) individual interfaces instead a whole device in contrast to the device authorization. If a deauthorized interface will be authorized so the driver probing must be triggered manually by writing INTERFACE to /sys/bus/usb/drivers_probe This allows to avoid side-effects with drivers that need multiple interfaces. A deauthorized interface cannot be probed or claimed. What: /sys/bus/usb/devices/usbX/interface_authorized_default Date: August 2015 Description: This is used as value that determines if interfaces would be authorized by default. The value can be 1 or 0. It's by default 1. What: /sys/bus/usb/device/.../authorized Date: July 2008 KernelVersion: 2.6.26 Contact: David Vrabel Description: Authorized devices are available for use by device drivers, non-authorized one are not. By default, wired USB devices are authorized. Certified Wireless USB devices are not authorized initially and should be (by writing 1) after the device has been authenticated. What: /sys/bus/usb/device/.../wusb_cdid Date: July 2008 KernelVersion: 2.6.27 Contact: David Vrabel Description: For Certified Wireless USB devices only. A devices's CDID, as 16 space-separated hex octets. What: /sys/bus/usb/device/.../wusb_ck Date: July 2008 KernelVersion: 2.6.27 Contact: David Vrabel Description: For Certified Wireless USB devices only. Write the device's connection key (CK) to start the authentication of the device. The CK is 16 space-separated hex octets. What: /sys/bus/usb/device/.../wusb_disconnect Date: July 2008 KernelVersion: 2.6.27 Contact: David Vrabel Description: For Certified Wireless USB devices only. Write a 1 to force the device to disconnect (equivalent to unplugging a wired USB device). What: /sys/bus/usb/drivers/.../new_id Date: October 2011 Contact: linux-usb@vger.kernel.org Description: Writing a device ID to this file will attempt to dynamically add a new device ID to a USB device driver. This may allow the driver to support more hardware than was included in the driver's static device ID support table at compile time. The format for the device ID is: idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct The vendor ID and device ID fields are required, the rest is optional. The Ref* tuple can be used to tell the driver to use the same driver_data for the new device as it is used for the reference device. Upon successfully adding an ID, the driver will probe for the device and attempt to bind to it. For example: # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id Here add a new device (0458:7045) using driver_data from an already supported device (0458:704c): # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id Reading from this file will list all dynamically added device IDs in the same format, with one entry per line. For example: # cat /sys/bus/usb/drivers/foo/new_id 8086 10f5 dead beef 06 f00d cafe The list will be truncated at PAGE_SIZE bytes due to sysfs restrictions. What: /sys/bus/usb-serial/drivers/.../new_id Date: October 2011 Contact: linux-usb@vger.kernel.org Description: For serial USB drivers, this attribute appears under the extra bus folder "usb-serial" in sysfs; apart from that difference, all descriptions from the entry "/sys/bus/usb/drivers/.../new_id" apply. What: /sys/bus/usb/drivers/.../remove_id Date: November 2009 Contact: CHENG Renquan Description: Writing a device ID to this file will remove an ID that was dynamically added via the new_id sysfs entry. The format for the device ID is: idVendor idProduct. After successfully removing an ID, the driver will no longer support the device. This is useful to ensure auto probing won't match the driver to the device. For example: # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id Reading from this file will list the dynamically added device IDs, exactly like reading from the entry "/sys/bus/usb/drivers/.../new_id" What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm Date: September 2011 Contact: Andiry Xu Description: If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged in to a xHCI host which support link PM, it will perform a LPM test; if the test is passed and host supports USB2 hardware LPM (xHCI 1.0 feature), USB2 hardware LPM will be enabled for the device and the USB device directory will contain a file named power/usb2_hardware_lpm. The file holds a string value (enable or disable) indicating whether or not USB2 hardware LPM is enabled for the device. Developer can write y/Y/1 or n/N/0 to the file to enable/disable the feature. What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1 /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2 Date: November 2015 Contact: Kevin Strasser Lu Baolu Description: If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged in to a xHCI host which supports link PM, it will check if U1 and U2 exit latencies have been set in the BOS descriptor; if the check is passed and the host supports USB3 hardware LPM, USB3 hardware LPM will be enabled for the device and the USB device directory will contain two files named power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These files hold a string value (enable or disable) indicating whether or not USB3 hardware LPM U1 or U2 is enabled for the device. What: /sys/bus/usb/devices/.../removable Date: February 2012 Contact: Matthew Garrett Description: Some information about whether a given USB device is physically fixed to the platform can be inferred from a combination of hub descriptor bits and platform-specific data such as ACPI. This file will read either "removable" or "fixed" if the information is available, and "unknown" otherwise. What: /sys/bus/usb/devices/.../ltm_capable Date: July 2012 Contact: Sarah Sharp Description: USB 3.0 devices may optionally support Latency Tolerance Messaging (LTM). They indicate their support by setting a bit in the bmAttributes field of their SuperSpeed BOS descriptors. If that bit is set for the device, ltm_capable will read "yes". If the device doesn't support LTM, the file will read "no". The file will be present for all speeds of USB devices, and will always read "no" for USB 1.1 and USB 2.0 devices. What: /sys/bus/usb/devices/.../(hub interface)/portX Date: August 2012 Contact: Lan Tianyu Description: The /sys/bus/usb/devices/.../(hub interface)/portX is usb port device's sysfs directory. What: /sys/bus/usb/devices/.../(hub interface)/portX/connect_type Date: January 2013 Contact: Lan Tianyu Description: Some platforms provide usb port connect types through ACPI. This attribute is to expose these information to user space. The file will read "hotplug", "wired" and "not used" if the information is available, and "unknown" otherwise. What: /sys/bus/usb/devices/.../(hub interface)/portX/quirks Date: May 2018 Contact: Nicolas Boichat Description: In some cases, we care about time-to-active for devices connected on a specific port (e.g. non-standard USB port like pogo pins), where the device to be connected is known in advance, and behaves well according to the specification. This attribute is a bit-field that controls the behavior of a specific port: - Bit 0 of this field selects the "old" enumeration scheme, as it is considerably faster (it only causes one USB reset instead of 2). The old enumeration scheme can also be selected globally using /sys/module/usbcore/parameters/old_scheme_first, but it is often not desirable as the new scheme was introduced to increase compatibility with more devices. - Bit 1 reduces TRSTRCY to the 10 ms that are required by the USB 2.0 specification, instead of the 50 ms that are normally used to help make enumeration work better on some high speed devices. What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count Date: February 2018 Contact: Richard Leitner Description: Most hubs are able to detect over-current situations on their ports and report them to the kernel. This attribute is to expose the number of over-current situation occurred on a specific port to user space. This file will contain an unsigned 32 bit value which wraps to 0 after its maximum is reached. This file supports poll() for monitoring changes to this value in user space. Any time this value changes the corresponding hub device will send a udev event with the following attributes: OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX OVER_CURRENT_COUNT=[current value of this sysfs attribute] What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit Date: November 2015 Contact: Lu Baolu Description: Some USB3.0 devices are not friendly to USB3 LPM. usb3_lpm_permit attribute allows enabling/disabling usb3 lpm of a port. It takes effect both before and after a usb device is enumerated. Supported values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1 is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and u2 are permitted. What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout Date: May 2013 Contact: Mathias Nyman Description: USB 2.0 devices may support hardware link power management (LPM) L1 sleep state. The usb2_lpm_l1_timeout attribute allows tuning the timeout for L1 inactivity timer (LPM timer), e.g. needed inactivity time before host requests the device to go to L1 sleep. Useful for power management tuning. Supported values are 0 - 65535 microseconds. What: /sys/bus/usb/devices/.../power/usb2_lpm_besl Date: May 2013 Contact: Mathias Nyman Description: USB 2.0 devices that support hardware link power management (LPM) L1 sleep state now use a best effort service latency value (BESL) to indicate the best effort to resumption of service to the device after the initiation of the resume event. If the device does not have a preferred besl value then the host can select one instead. This usb2_lpm_besl attribute allows to tune the host selected besl value in order to tune power saving and service latency. Supported values are 0 - 15. More information on how besl values map to microseconds can be found in USB 2.0 ECN Errata for Link Power Management, section 4.10) What: /sys/bus/usb/devices/.../rx_lanes Date: March 2018 Contact: Mathias Nyman Description: Number of rx lanes the device is using. USB 3.2 adds Dual-lane support, 2 rx and 2 tx lanes over Type-C. Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per direction. Devices before USB 3.2 are single lane (rx_lanes = 1) What: /sys/bus/usb/devices/.../tx_lanes Date: March 2018 Contact: Mathias Nyman Description: Number of tx lanes the device is using. USB 3.2 adds Dual-lane support, 2 rx and 2 tx -lanes over Type-C. Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per direction. Devices before USB 3.2 are single lane (tx_lanes = 1)