What: /sys/bus/usb/devices/.../power/autosuspend Date: March 2007 KernelVersion: 2.6.21 Contact: Alan Stern Description: Each USB device directory will contain a file named power/autosuspend. This file holds the time (in seconds) the device must be idle before it will be autosuspended. 0 means the device will be autosuspended as soon as possible. Negative values will prevent the device from being autosuspended at all, and writing a negative value will resume the device if it is already suspended. The autosuspend delay for newly-created devices is set to the value of the usbcore.autosuspend module parameter. What: /sys/bus/usb/devices/.../power/persist Date: May 2007 KernelVersion: 2.6.23 Contact: Alan Stern Description: If CONFIG_USB_PERSIST is set, then each USB device directory will contain a file named power/persist. The file holds a boolean value (0 or 1) indicating whether or not the "USB-Persist" facility is enabled for the device. Since the facility is inherently dangerous, it is disabled by default for all devices except hubs. For more information, see Documentation/usb/persist.txt. What: /sys/bus/usb/device/.../power/connected_duration Date: January 2008 KernelVersion: 2.6.25 Contact: Sarah Sharp Description: If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file is present. When read, it returns the total time (in msec) that the USB device has been connected to the machine. This file is read-only. Users: PowerTOP http://www.lesswatts.org/projects/powertop/ What: /sys/bus/usb/device/.../power/active_duration Date: January 2008 KernelVersion: 2.6.25 Contact: Sarah Sharp Description: If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file is present. When read, it returns the total time (in msec) that the USB device has been active, i.e. not in a suspended state. This file is read-only. Tools can use this file and the connected_duration file to compute the percentage of time that a device has been active. For example, echo $((100 * `cat active_duration` / `cat connected_duration`)) will give an integer percentage. Note that this does not account for counter wrap. Users: PowerTOP http://www.lesswatts.org/projects/powertop/ What: /sys/bus/usb/device/-...:-/supports_autosuspend Date: January 2008 KernelVersion: 2.6.27 Contact: Sarah Sharp Description: When read, this file returns 1 if the interface driver for this interface supports autosuspend. It also returns 1 if no driver has claimed this interface, as an unclaimed interface will not stop the device from being autosuspended if all other interface drivers are idle. The file returns 0 if autosuspend support has not been added to the driver. Users: USB PM tool git://git.moblin.org/users/sarah/usb-pm-tool/ 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. The vendor ID and device ID fields are required, the interface class is optional. 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 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/device/.../avoid_reset_quirk Date: December 2009 Contact: Oliver Neukum Description: Writing 1 to this file tells the kernel that this device will morph into another mode when it is reset. Drivers will not use reset for error handling for such devices. Users: usb_modeswitch What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm Date: September 2011 Contact: Andiry Xu Description: If CONFIG_USB_SUSPEND 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/.../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.