Documentation/ABI/stable/sysfs-bus-usb

   1 What:           /sys/bus/usb/devices/.../power/persist
   2 Date:           May 2007
   3 KernelVersion:  2.6.23
   4 Contact:        Alan Stern <stern@rowland.harvard.edu>
   5 Description:
   6                 USB device directories can contain a file named power/persist.
   7                 The file holds a boolean value (0 or 1) indicating whether or
   8                 not the "USB-Persist" facility is enabled for the device.  For
   9                 hubs this facility is always enabled and their device
  10                 directories will not contain this file.
  11
  12                 For more information, see Documentation/usb/persist.txt.
  13
  14 What:           /sys/bus/usb/devices/.../power/autosuspend
  15 Date:           March 2007
  16 KernelVersion:  2.6.21
  17 Contact:        Alan Stern <stern@rowland.harvard.edu>
  18 Description:
  19                 Each USB device directory will contain a file named
  20                 power/autosuspend.  This file holds the time (in seconds)
  21                 the device must be idle before it will be autosuspended.
  22                 0 means the device will be autosuspended as soon as
  23                 possible.  Negative values will prevent the device from
  24                 being autosuspended at all, and writing a negative value
  25                 will resume the device if it is already suspended.
  26
  27                 The autosuspend delay for newly-created devices is set to
  28                 the value of the usbcore.autosuspend module parameter.
  29
  30 What:           /sys/bus/usb/device/.../power/connected_duration
  31 Date:           January 2008
  32 KernelVersion:  2.6.25
  33 Contact:        Sarah Sharp <sarah.a.sharp@intel.com>
  34 Description:
  35                 If CONFIG_PM is enabled, then this file is present.  When read,
  36                 it returns the total time (in msec) that the USB device has been
  37                 connected to the machine.  This file is read-only.
  38 Users:
  39                 PowerTOP <powertop@lists.01.org>
  40                 https://01.org/powertop/
  41
  42 What:           /sys/bus/usb/device/.../power/active_duration
  43 Date:           January 2008
  44 KernelVersion:  2.6.25
  45 Contact:        Sarah Sharp <sarah.a.sharp@intel.com>
  46 Description:
  47                 If CONFIG_PM is enabled, then this file is present.  When read,
  48                 it returns the total time (in msec) that the USB device has been
  49                 active, i.e. not in a suspended state.  This file is read-only.
  50
  51                 Tools can use this file and the connected_duration file to
  52                 compute the percentage of time that a device has been active.
  53                 For example,
  54                 echo $((100 * `cat active_duration` / `cat connected_duration`))
  55                 will give an integer percentage.  Note that this does not
  56                 account for counter wrap.
  57 Users:
  58                 PowerTOP <powertop@lists.01.org>
  59                 https://01.org/powertop/
  60
  61 What:           /sys/bus/usb/devices/<busnum>-<port[.port]>...:<config num>-<interface num>/supports_autosuspend
  62 Date:           January 2008
  63 KernelVersion:  2.6.27
  64 Contact:        Sarah Sharp <sarah.a.sharp@intel.com>
  65 Description:
  66                 When read, this file returns 1 if the interface driver
  67                 for this interface supports autosuspend.  It also
  68                 returns 1 if no driver has claimed this interface, as an
  69                 unclaimed interface will not stop the device from being
  70                 autosuspended if all other interface drivers are idle.
  71                 The file returns 0 if autosuspend support has not been
  72                 added to the driver.
  73 Users:
  74                 USB PM tool
  75                 git://git.moblin.org/users/sarah/usb-pm-tool/
  76
  77 What:           /sys/bus/usb/device/.../avoid_reset_quirk
  78 Date:           December 2009
  79 Contact:        Oliver Neukum <oliver@neukum.org>
  80 Description:
  81                 Writing 1 to this file tells the kernel that this
  82                 device will morph into another mode when it is reset.
  83                 Drivers will not use reset for error handling for
  84                 such devices.
  85 Users:
  86                 usb_modeswitch
  87
  88 What:           /sys/bus/usb/devices/.../devnum
  89 KernelVersion:  since at least 2.6.18
  90 Description:
  91                 Device address on the USB bus.
  92 Users:
  93                 libusb
  94
  95 What:           /sys/bus/usb/devices/.../bConfigurationValue
  96 KernelVersion:  since at least 2.6.18
  97 Description:
  98                 bConfigurationValue of the *active* configuration for the
  99                 device. Writing 0 or -1 to bConfigurationValue will reset the
 100                 active configuration (unconfigure the device). Writing
 101                 another value will change the active configuration.
 102
 103                 Note that some devices, in violation of the USB spec, have a
 104                 configuration with a value equal to 0. Writing 0 to
 105                 bConfigurationValue for these devices will install that
 106                 configuration, rather then unconfigure the device.
 107
 108                 Writing -1 will always unconfigure the device.
 109 Users:
 110                 libusb
 111
 112 What:           /sys/bus/usb/devices/.../busnum
 113 KernelVersion:  2.6.22
 114 Description:
 115                 Bus-number of the USB-bus the device is connected to.
 116 Users:
 117                 libusb
 118
 119 What:           /sys/bus/usb/devices/.../descriptors
 120 KernelVersion:  2.6.26
 121 Description:
 122                 Binary file containing cached descriptors of the device. The
 123                 binary data consists of the device descriptor followed by the
 124                 descriptors for each configuration of the device.
 125                 Note that the wTotalLength of the config descriptors can not
 126                 be trusted, as the device may have a smaller config descriptor
 127                 than it advertises. The bLength field of each (sub) descriptor
 128                 can be trusted, and can be used to seek forward one (sub)
 129                 descriptor at a time until the next config descriptor is found.
 130                 All descriptors read from this file are in bus-endian format
 131 Users:
 132                 libusb
 133
 134 What:           /sys/bus/usb/devices/.../speed
 135 KernelVersion:  since at least 2.6.18
 136 Description:
 137                 Speed the device is connected with to the usb-host in
 138                 Mbit / second. IE one of 1.5 / 12 / 480 / 5000.
 139 Users:
 140                 libusb