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_RUNTIME is enabled then this file
  36                 is present.  When read, it returns the total time (in msec)
  37                 that the USB device has been connected to the machine.  This
  38                 file is read-only.
  39 Users:
  40                 PowerTOP <powertop@lists.01.org>
  41                 https://01.org/powertop/
  42
  43 What:           /sys/bus/usb/device/.../power/active_duration
  44 Date:           January 2008
  45 KernelVersion:  2.6.25
  46 Contact:        Sarah Sharp <sarah.a.sharp@intel.com>
  47 Description:
  48                 If CONFIG_PM_RUNTIME is enabled then this file
  49                 is present.  When read, it returns the total time (in msec)
  50                 that the USB device has been active, i.e. not in a suspended
  51                 state.  This file is read-only.
  52
  53                 Tools can use this file and the connected_duration file to
  54                 compute the percentage of time that a device has been active.
  55                 For example,
  56                 echo $((100 * `cat active_duration` / `cat connected_duration`))
  57                 will give an integer percentage.  Note that this does not
  58                 account for counter wrap.
  59 Users:
  60                 PowerTOP <powertop@lists.01.org>
  61                 https://01.org/powertop/
  62
  63 What:           /sys/bus/usb/devices/<busnum>-<port[.port]>...:<config num>-<interface num>/supports_autosuspend
  64 Date:           January 2008
  65 KernelVersion:  2.6.27
  66 Contact:        Sarah Sharp <sarah.a.sharp@intel.com>
  67 Description:
  68                 When read, this file returns 1 if the interface driver
  69                 for this interface supports autosuspend.  It also
  70                 returns 1 if no driver has claimed this interface, as an
  71                 unclaimed interface will not stop the device from being
  72                 autosuspended if all other interface drivers are idle.
  73                 The file returns 0 if autosuspend support has not been
  74                 added to the driver.
  75 Users:
  76                 USB PM tool
  77                 git://git.moblin.org/users/sarah/usb-pm-tool/
  78
  79 What:           /sys/bus/usb/device/.../avoid_reset_quirk
  80 Date:           December 2009
  81 Contact:        Oliver Neukum <oliver@neukum.org>
  82 Description:
  83                 Writing 1 to this file tells the kernel that this
  84                 device will morph into another mode when it is reset.
  85                 Drivers will not use reset for error handling for
  86                 such devices.
  87 Users:
  88                 usb_modeswitch
  89
  90 What:           /sys/bus/usb/devices/.../devnum
  91 KernelVersion:  since at least 2.6.18
  92 Description:
  93                 Device address on the USB bus.
  94 Users:
  95                 libusb
  96
  97 What:           /sys/bus/usb/devices/.../bConfigurationValue
  98 KernelVersion:  since at least 2.6.18
  99 Description:
 100                 bConfigurationValue of the *active* configuration for the
 101                 device. Writing 0 or -1 to bConfigurationValue will reset the
 102                 active configuration (unconfigure the device). Writing
 103                 another value will change the active configuration.
 104
 105                 Note that some devices, in violation of the USB spec, have a
 106                 configuration with a value equal to 0. Writing 0 to
 107                 bConfigurationValue for these devices will install that
 108                 configuration, rather then unconfigure the device.
 109
 110                 Writing -1 will always unconfigure the device.
 111 Users:
 112                 libusb
 113
 114 What:           /sys/bus/usb/devices/.../busnum
 115 KernelVersion:  2.6.22
 116 Description:
 117                 Bus-number of the USB-bus the device is connected to.
 118 Users:
 119                 libusb
 120
 121 What:           /sys/bus/usb/devices/.../descriptors
 122 KernelVersion:  2.6.26
 123 Description:
 124                 Binary file containing cached descriptors of the device. The
 125                 binary data consists of the device descriptor followed by the
 126                 descriptors for each configuration of the device.
 127                 Note that the wTotalLength of the config descriptors can not
 128                 be trusted, as the device may have a smaller config descriptor
 129                 than it advertises. The bLength field of each (sub) descriptor
 130                 can be trusted, and can be used to seek forward one (sub)
 131                 descriptor at a time until the next config descriptor is found.
 132                 All descriptors read from this file are in bus-endian format
 133 Users:
 134                 libusb
 135
 136 What:           /sys/bus/usb/devices/.../speed
 137 KernelVersion:  since at least 2.6.18
 138 Description:
 139                 Speed the device is connected with to the usb-host in
 140                 Mbit / second. IE one of 1.5 / 12 / 480 / 5000.
 141 Users:
 142                 libusb