| 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 |