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Diffstat (limited to 'Documentation/ABI/stable/sysfs-bus-usb')
| -rw-r--r-- | Documentation/ABI/stable/sysfs-bus-usb | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/Documentation/ABI/stable/sysfs-bus-usb b/Documentation/ABI/stable/sysfs-bus-usb new file mode 100644 index 00000000000..6b59aeaee75 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-bus-usb @@ -0,0 +1,126 @@ +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 <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_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 <power@bughost.org> + http://www.lesswatts.org/projects/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. + +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. + +What: /sys/bus/usb/devices/.../busnum +KernelVersion: 2.6.22 +Description: + Bus-number of the USB-bus the device is connected to. + +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 |