| 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/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/device/.../power/connected_duration | |
| Date: January 2008 | |
| KernelVersion: 2.6.25 | |
| Contact: Sarah Sharp <sarah.a.sharp@intel.com> | |
| Description: | |
| If CONFIG_PM_RUNTIME is 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 <powertop@lists.01.org> | |
| https://01.org/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_RUNTIME is 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 <powertop@lists.01.org> | |
| https://01.org/powertop/ | |
| What: /sys/bus/usb/devices/<busnum>-<port[.port]>...:<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/.../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 | |
| What: /sys/bus/usb/devices/.../devnum | |
| KernelVersion: since at least 2.6.18 | |
| Description: | |
| Device address on the USB bus. | |
| Users: | |
| libusb | |
| What: /sys/bus/usb/devices/.../bConfigurationValue | |
| KernelVersion: since at least 2.6.18 | |
| Description: | |
| bConfigurationValue of the *active* configuration for the | |
| device. Writing 0 or -1 to bConfigurationValue will reset the | |
| active configuration (unconfigure the device). Writing | |
| another value will change the active configuration. | |
| Note that some devices, in violation of the USB spec, have a | |
| configuration with a value equal to 0. Writing 0 to | |
| bConfigurationValue for these devices will install that | |
| configuration, rather then unconfigure the device. | |
| Writing -1 will always unconfigure the device. | |
| Users: | |
| libusb | |
| What: /sys/bus/usb/devices/.../busnum | |
| KernelVersion: 2.6.22 | |
| Description: | |
| Bus-number of the USB-bus the device is connected to. | |
| Users: | |
| libusb | |
| What: /sys/bus/usb/devices/.../descriptors | |
| KernelVersion: 2.6.26 | |
| Description: | |
| Binary file containing cached descriptors of the device. The | |
| binary data consists of the device descriptor followed by the | |
| descriptors for each configuration of the device. | |
| Note that the wTotalLength of the config descriptors can not | |
| be trusted, as the device may have a smaller config descriptor | |
| than it advertises. The bLength field of each (sub) descriptor | |
| can be trusted, and can be used to seek forward one (sub) | |
| descriptor at a time until the next config descriptor is found. | |
| All descriptors read from this file are in bus-endian format | |
| Users: | |
| libusb | |
| What: /sys/bus/usb/devices/.../speed | |
| KernelVersion: since at least 2.6.18 | |
| Description: | |
| Speed the device is connected with to the usb-host in | |
| Mbit / second. IE one of 1.5 / 12 / 480 / 5000. | |
| Users: | |
| libusb |