What: /sys/bus/usb/devices/.../power/autosuspend Date: March 2007 KernelVersion: 2.6.21 Contact: Alan Stern <stern@rowland.harvard.edu> 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 <stern@rowland.harvard.edu> 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 <sarah.a.sharp@intel.com> 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 <power@bughost.org> http://www.lesswatts.org/projects/powertop/ What: /sys/bus/usb/device/.../power/active_duration Date: January 2008 KernelVersion: 2.6.25 Contact: Sarah Sharp <sarah.a.sharp@intel.com> 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 <power@bughost.org> http://www.lesswatts.org/projects/powertop/ What: /sys/bus/usb/device/<busnum>-<devnum>...:<config num>-<interface num>/supports_autosuspend Date: January 2008 KernelVersion: 2.6.27 Contact: Sarah Sharp <sarah.a.sharp@intel.com> 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 <david.vrabel@csr.com> 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 <david.vrabel@csr.com> 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 <david.vrabel@csr.com> 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 <david.vrabel@csr.com> 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/.../remove_id Date: November 2009 Contact: CHENG Renquan <rqcheng@smu.edu.sg> 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 What: /sys/bus/usb/device/.../avoid_reset_quirk Date: December 2009 Contact: Oliver Neukum <oliver@neukum.org> 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