Documentation/ABI/testing/sysfs-bus-usb

   1 What:           /sys/bus/usb/devices/<INTERFACE>/authorized
   2 Date:           August 2015
   3 Description:
   4                 This allows to authorize (1) or deauthorize (0)
   5                 individual interfaces instead a whole device
   6                 in contrast to the device authorization.
   7                 If a deauthorized interface will be authorized
   8                 so the driver probing must be triggered manually
   9                 by writing INTERFACE to /sys/bus/usb/drivers_probe
  10                 This allows to avoid side-effects with drivers
  11                 that need multiple interfaces.
  12
  13                 A deauthorized interface cannot be probed or claimed.
  14
  15 What:           /sys/bus/usb/devices/usbX/interface_authorized_default
  16 Date:           August 2015
  17 Description:
  18                 This is used as value that determines if interfaces
  19                 would be authorized by default.
  20                 The value can be 1 or 0. It's by default 1.
  21
  22 What:           /sys/bus/usb/device/.../authorized
  23 Date:           July 2008
  24 KernelVersion:  2.6.26
  25 Contact:        David Vrabel <david.vrabel@csr.com>
  26 Description:
  27                 Authorized devices are available for use by device
  28                 drivers, non-authorized one are not.  By default, wired
  29                 USB devices are authorized.
  30
  31 What:           /sys/bus/usb/drivers/.../new_id
  32 Date:           October 2011
  33 Contact:        linux-usb@vger.kernel.org
  34 Description:
  35                 Writing a device ID to this file will attempt to
  36                 dynamically add a new device ID to a USB device driver.
  37                 This may allow the driver to support more hardware than
  38                 was included in the driver's static device ID support
  39                 table at compile time. The format for the device ID is:
  40                 idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct
  41                 The vendor ID and device ID fields are required, the
  42                 rest is optional. The `Ref*` tuple can be used to tell the
  43                 driver to use the same driver_data for the new device as
  44                 it is used for the reference device.
  45                 Upon successfully adding an ID, the driver will probe
  46                 for the device and attempt to bind to it.  For example::
  47
  48                   # echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
  49
  50                 Here add a new device (0458:7045) using driver_data from
  51                 an already supported device (0458:704c)::
  52
  53                   # echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id
  54
  55                 Reading from this file will list all dynamically added
  56                 device IDs in the same format, with one entry per
  57                 line. For example::
  58
  59                   # cat /sys/bus/usb/drivers/foo/new_id
  60                   8086 10f5
  61                   dead beef 06
  62                   f00d cafe
  63
  64                 The list will be truncated at PAGE_SIZE bytes due to
  65                 sysfs restrictions.
  66
  67 What:           /sys/bus/usb-serial/drivers/.../new_id
  68 Date:           October 2011
  69 Contact:        linux-usb@vger.kernel.org
  70 Description:
  71                 For serial USB drivers, this attribute appears under the
  72                 extra bus folder "usb-serial" in sysfs; apart from that
  73                 difference, all descriptions from the entry
  74                 "/sys/bus/usb/drivers/.../new_id" apply.
  75
  76 What:           /sys/bus/usb/drivers/.../remove_id
  77 Date:           November 2009
  78 Contact:        CHENG Renquan <rqcheng@smu.edu.sg>
  79 Description:
  80                 Writing a device ID to this file will remove an ID
  81                 that was dynamically added via the new_id sysfs entry.
  82                 The format for the device ID is:
  83                 idVendor idProduct.     After successfully
  84                 removing an ID, the driver will no longer support the
  85                 device.  This is useful to ensure auto probing won't
  86                 match the driver to the device.  For example:
  87                 # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
  88
  89                 Reading from this file will list the dynamically added
  90                 device IDs, exactly like reading from the entry
  91                 "/sys/bus/usb/drivers/.../new_id"
  92
  93 What:           /sys/bus/usb/devices/.../power/usb2_hardware_lpm
  94 Date:           September 2011
  95 Contact:        Andiry Xu <andiry.xu@amd.com>
  96 Description:
  97                 If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged
  98                 in to a xHCI host which support link PM, it will perform a LPM
  99                 test; if the test is passed and host supports USB2 hardware LPM
 100                 (xHCI 1.0 feature), USB2 hardware LPM will be enabled for the
 101                 device and the USB device directory will contain a file named
 102                 power/usb2_hardware_lpm.  The file holds a string value (enable
 103                 or disable) indicating whether or not USB2 hardware LPM is
 104                 enabled for the device. Developer can write y/Y/1 or n/N/0 to
 105                 the file to enable/disable the feature.
 106
 107 What:           /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
 108                 /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
 109 Date:           November 2015
 110 Contact:        Kevin Strasser <kevin.strasser@linux.intel.com>
 111                 Lu Baolu <baolu.lu@linux.intel.com>
 112 Description:
 113                 If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
 114                 in to a xHCI host which supports link PM, it will check if U1
 115                 and U2 exit latencies have been set in the BOS descriptor; if
 116                 the check is passed and the host supports USB3 hardware LPM,
 117                 USB3 hardware LPM will be enabled for the device and the USB
 118                 device directory will contain two files named
 119                 power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
 120                 files hold a string value (enable or disable) indicating whether
 121                 or not USB3 hardware LPM U1 or U2 is enabled for the device.
 122
 123 What:           /sys/bus/usb/devices/.../ltm_capable
 124 Date:           July 2012
 125 Contact:        Sarah Sharp <sarah.a.sharp@linux.intel.com>
 126 Description:
 127                 USB 3.0 devices may optionally support Latency Tolerance
 128                 Messaging (LTM).  They indicate their support by setting a bit
 129                 in the bmAttributes field of their SuperSpeed BOS descriptors.
 130                 If that bit is set for the device, ltm_capable will read "yes".
 131                 If the device doesn't support LTM, the file will read "no".
 132                 The file will be present for all speeds of USB devices, and will
 133                 always read "no" for USB 1.1 and USB 2.0 devices.
 134
 135 What:           /sys/bus/usb/devices/<INTERFACE>/wireless_status
 136 Date:           February 2023
 137 Contact:        Bastien Nocera <hadess@hadess.net>
 138 Description:
 139                 Some USB devices use a USB receiver dongle to communicate
 140                 wirelessly with their device using proprietary protocols. This
 141                 attribute allows user-space to know whether the device is
 142                 connected to its receiver dongle, and, for example, consider
 143                 the device to be absent when choosing whether to show the
 144                 device's battery, show a headset in a list of outputs, or show
 145                 an on-screen keyboard if the only wireless keyboard is
 146                 turned off.
 147                 This attribute is not to be used to replace protocol specific
 148                 statuses available in WWAN, WLAN/Wi-Fi, Bluetooth, etc.
 149                 If the device does not use a receiver dongle with a wireless
 150                 device, then this attribute will not exist.
 151
 152 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>
 153 Date:           August 2012
 154 Contact:        Lan Tianyu <tianyu.lan@intel.com>
 155 Description:
 156                 The /sys/bus/usb/devices/.../<hub_interface>/port<X>
 157                 is usb port device's sysfs directory.
 158
 159 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/connect_type
 160 Date:           January 2013
 161 Contact:        Lan Tianyu <tianyu.lan@intel.com>
 162 Description:
 163                 Some platforms provide usb port connect types through ACPI.
 164                 This attribute is to expose these information to user space.
 165                 The file will read "hotplug", "hardwired" and "not used" if the
 166                 information is available, and "unknown" otherwise.
 167
 168 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/location
 169 Date:           October 2018
 170 Contact:        Bjørn Mork <bjorn@mork.no>
 171 Description:
 172                 Some platforms provide usb port physical location through
 173                 firmware. This is used by the kernel to pair up logical ports
 174                 mapping to the same physical connector. The attribute exposes the
 175                 raw location value as a hex integer.
 176
 177
 178 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/quirks
 179 Date:           May 2018
 180 Contact:        Nicolas Boichat <drinkcat@chromium.org>
 181 Description:
 182                 In some cases, we care about time-to-active for devices
 183                 connected on a specific port (e.g. non-standard USB port like
 184                 pogo pins), where the device to be connected is known in
 185                 advance, and behaves well according to the specification.
 186                 This attribute is a bit-field that controls the behavior of
 187                 a specific port:
 188
 189                  - Bit 0 of this field selects the "old" enumeration scheme,
 190                    as it is considerably faster (it only causes one USB reset
 191                    instead of 2).
 192
 193                    The old enumeration scheme can also be selected globally
 194                    using /sys/module/usbcore/parameters/old_scheme_first, but
 195                    it is often not desirable as the new scheme was introduced to
 196                    increase compatibility with more devices.
 197                  - Bit 1 reduces TRSTRCY to the 10 ms that are required by the
 198                    USB 2.0 specification, instead of the 50 ms that are normally
 199                    used to help make enumeration work better on some high speed
 200                    devices.
 201
 202 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/over_current_count
 203 Date:           February 2018
 204 Contact:        Richard Leitner <richard.leitner@skidata.com>
 205 Description:
 206                 Most hubs are able to detect over-current situations on their
 207                 ports and report them to the kernel. This attribute is to expose
 208                 the number of over-current situation occurred on a specific port
 209                 to user space. This file will contain an unsigned 32 bit value
 210                 which wraps to 0 after its maximum is reached. This file supports
 211                 poll() for monitoring changes to this value in user space.
 212
 213                 Any time this value changes the corresponding hub device will send a
 214                 udev event with the following attributes::
 215
 216                   OVER_CURRENT_PORT=/sys/bus/usb/devices/.../<hub_interface>/port<X>
 217                   OVER_CURRENT_COUNT=[current value of this sysfs attribute]
 218
 219 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/usb3_lpm_permit
 220 Date:           November 2015
 221 Contact:        Lu Baolu <baolu.lu@linux.intel.com>
 222 Description:
 223                 Some USB3.0 devices are not friendly to USB3 LPM.  usb3_lpm_permit
 224                 attribute allows enabling/disabling usb3 lpm of a port. It takes
 225                 effect both before and after a usb device is enumerated. Supported
 226                 values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1
 227                 is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and
 228                 u2 are permitted.
 229
 230 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/connector
 231 Date:           December 2021
 232 Contact:        Heikki Krogerus <heikki.krogerus@linux.intel.com>
 233 Description:
 234                 Link to the USB Type-C connector when available. This link is
 235                 only created when USB Type-C Connector Class is enabled, and
 236                 only if the system firmware is capable of describing the
 237                 connection between a port and its connector.
 238
 239 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/disable
 240 Date:           June 2022
 241 Contact:        Michael Grzeschik <m.grzeschik@pengutronix.de>
 242 Description:
 243                 This file controls the state of a USB port, including
 244                 Vbus power output (but only on hubs that support
 245                 power switching -- most hubs don't support it). If
 246                 a port is disabled, the port is unusable: Devices
 247                 attached to the port will not be detected, initialized,
 248                 or enumerated.
 249
 250 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/early_stop
 251 Date:           Sep 2022
 252 Contact:        Ray Chi <raychi@google.com>
 253 Description:
 254                 Some USB hosts have some watchdog mechanisms so that the device
 255                 may enter ramdump if it takes a long time during port initialization.
 256                 This attribute allows each port just has two attempts so that the
 257                 port initialization will be failed quickly. In addition, if a port
 258                 which is marked with early_stop has failed to initialize, it will ignore
 259                 all future connections until this attribute is clear.
 260
 261 What:           /sys/bus/usb/devices/.../<hub_interface>/port<X>/state
 262 Date:           June 2023
 263 Contact:        Roy Luo <royluo@google.com>
 264 Description:
 265                 Indicates current state of the USB device attached to the port.
 266                 Valid states are: 'not-attached', 'attached', 'powered',
 267                 'reconnecting', 'unauthenticated', 'default', 'addressed',
 268                 'configured', and 'suspended'. This file supports poll() to
 269                 monitor the state change from user space.
 270
 271 What:           /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
 272 Date:           May 2013
 273 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 274 Description:
 275                 USB 2.0 devices may support hardware link power management (LPM)
 276                 L1 sleep state. The usb2_lpm_l1_timeout attribute allows
 277                 tuning the timeout for L1 inactivity timer (LPM timer), e.g.
 278                 needed inactivity time before host requests the device to go to L1 sleep.
 279                 Useful for power management tuning.
 280                 Supported values are 0 - 65535 microseconds.
 281
 282 What:           /sys/bus/usb/devices/.../power/usb2_lpm_besl
 283 Date:           May 2013
 284 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 285 Description:
 286                 USB 2.0 devices that support hardware link power management (LPM)
 287                 L1 sleep state now use a best effort service latency value (BESL) to
 288                 indicate the best effort to resumption of service to the device after the
 289                 initiation of the resume event.
 290                 If the device does not have a preferred besl value then the host can select
 291                 one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
 292                 value in order to tune power saving and service latency.
 293
 294                 Supported values are 0 - 15.
 295                 More information on how besl values map to microseconds can be found in
 296                 USB 2.0 ECN Errata for Link Power Management, section 4.10)
 297
 298 What:           /sys/bus/usb/devices/.../rx_lanes
 299 Date:           March 2018
 300 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 301 Description:
 302                 Number of rx lanes the device is using.
 303                 USB 3.2 adds Dual-lane support, 2 rx and 2 tx lanes over Type-C.
 304                 Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per
 305                 direction. Devices before USB 3.2 are single lane (rx_lanes = 1)
 306
 307 What:           /sys/bus/usb/devices/.../tx_lanes
 308 Date:           March 2018
 309 Contact:        Mathias Nyman <mathias.nyman@linux.intel.com>
 310 Description:
 311                 Number of tx lanes the device is using.
 312                 USB 3.2 adds Dual-lane support, 2 rx and 2 tx -lanes over Type-C.
 313                 Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per
 314                 direction. Devices before USB 3.2 are single lane (tx_lanes = 1)
 315
 316 What:           /sys/bus/usb/devices/.../typec
 317 Date:           November 2023
 318 Contact:        Heikki Krogerus <heikki.krogerus@linux.intel.com>
 319 Description:
 320                 Symlink to the USB Type-C partner device. USB Type-C partner
 321                 represents the component that communicates over the
 322                 Configuration Channel (CC signal on USB Type-C connectors and
 323                 cables) with the local port.
 324
 325 What:           /sys/bus/usb/devices/usbX/bAlternateSetting
 326 Description:
 327                 The current interface alternate setting number, in decimal.
 328
 329                 See USB specs for its meaning.
 330
 331 What:           /sys/bus/usb/devices/usbX/bcdDevice
 332 Description:
 333                 The device's release number, in hexadecimal.
 334
 335                 See USB specs for its meaning.
 336
 337 What:           /sys/bus/usb/devices/usbX/bConfigurationValue
 338 Description:
 339                 While a USB device typically have just one configuration
 340                 setting, some devices support multiple configurations.
 341
 342                 This value shows the current configuration, in decimal.
 343
 344                 Changing its value will change the device's configuration
 345                 to another setting.
 346
 347                 The number of configurations supported by a device is at:
 348
 349                         /sys/bus/usb/devices/usbX/bNumConfigurations
 350
 351                 See USB specs for its meaning.
 352
 353 What:           /sys/bus/usb/devices/usbX/bDeviceClass
 354 Description:
 355                 Class code of the device, in hexadecimal.
 356
 357                 See USB specs for its meaning.
 358
 359 What:           /sys/bus/usb/devices/usbX/bDeviceProtocol
 360 Description:
 361                 Protocol code of the device, in hexadecimal.
 362
 363                 See USB specs for its meaning.
 364
 365 What:           /sys/bus/usb/devices/usbX/bDeviceSubClass
 366 Description:
 367                 Subclass code of the device, in hexadecimal.
 368
 369                 See USB specs for its meaning.
 370
 371 What:           /sys/bus/usb/devices/usbX/bInterfaceClass
 372 Description:
 373                 Class code of the interface, in hexadecimal.
 374
 375                 See USB specs for its meaning.
 376
 377 What:           /sys/bus/usb/devices/usbX/bInterfaceNumber
 378 Description:
 379                 Interface number, in hexadecimal.
 380
 381                 See USB specs for its meaning.
 382
 383 What:           /sys/bus/usb/devices/usbX/bInterfaceProtocol
 384 Description:
 385                 Protocol code of the interface, in hexadecimal.
 386
 387                 See USB specs for its meaning.
 388
 389 What:           /sys/bus/usb/devices/usbX/bInterfaceSubClass
 390 Description:
 391                 Subclass code of the interface, in hexadecimal.
 392
 393                 See USB specs for its meaning.
 394
 395 What:           /sys/bus/usb/devices/usbX/bmAttributes
 396 Description:
 397                 Attributes of the current configuration, in hexadecimal.
 398
 399                 See USB specs for its meaning.
 400
 401 What:           /sys/bus/usb/devices/usbX/bMaxPacketSize0
 402 Description:
 403                 Maximum endpoint 0 packet size, in decimal.
 404
 405                 See USB specs for its meaning.
 406
 407 What:           /sys/bus/usb/devices/usbX/bMaxPower
 408 Description:
 409                 Maximum power consumption of the active configuration of
 410                 the device, in miliamperes.
 411
 412 What:           /sys/bus/usb/devices/usbX/bNumConfigurations
 413 Description:
 414                 Number of the possible configurations of the device, in
 415                 decimal. The current configuration is controlled via:
 416
 417                         /sys/bus/usb/devices/usbX/bConfigurationValue
 418
 419                 See USB specs for its meaning.
 420
 421 What:           /sys/bus/usb/devices/usbX/bNumEndpoints
 422 Description:
 423                 Number of endpoints used on this interface, in hexadecimal.
 424
 425                 See USB specs for its meaning.
 426
 427 What:           /sys/bus/usb/devices/usbX/bNumInterfaces
 428 Description:
 429                 Number of interfaces on this device, in decimal.
 430
 431 What:           /sys/bus/usb/devices/usbX/busnum
 432 Description:
 433                 Number of the bus.
 434
 435 What:           /sys/bus/usb/devices/usbX/configuration
 436 Description:
 437                 Contents of the string descriptor associated with the
 438                 current configuration. It may include the firmware version
 439                 of a device and/or its serial number.
 440
 441 What:           /sys/bus/usb/devices/usbX/descriptors
 442 Description:
 443                 Contains the interface descriptors, in binary.
 444
 445 What:           /sys/bus/usb/devices/usbX/bos_descriptors
 446 Date:           March 2024
 447 Contact:        Elbert Mai <code@elbertmai.com>
 448 Description:
 449                 Binary file containing the cached binary device object store (BOS)
 450                 of the device. This consists of the BOS descriptor followed by the
 451                 set of device capability descriptors. All descriptors read from
 452                 this file are in bus-endian format. Note that the kernel will not
 453                 request the BOS from a device if its bcdUSB is less than 0x0201.
 454
 455 What:           /sys/bus/usb/devices/usbX/idProduct
 456 Description:
 457                 Product ID, in hexadecimal.
 458
 459 What:           /sys/bus/usb/devices/usbX/idVendor
 460 Description:
 461                 Vendor ID, in hexadecimal.
 462
 463 What:           /sys/bus/usb/devices/usbX/devspec
 464 Description:
 465                 Displays the Device Tree Open Firmware node of the interface.
 466
 467 What:           /sys/bus/usb/devices/usbX/avoid_reset_quirk
 468 Description:
 469                 Most devices have this set to zero.
 470
 471                 If the value is 1, enable a USB quirk that prevents this
 472                 device to use reset.
 473
 474                 (read/write)
 475
 476 What:           /sys/bus/usb/devices/usbX/devnum
 477 Description:
 478                 USB interface device number, in decimal.
 479
 480 What:           /sys/bus/usb/devices/usbX/devpath
 481 Description:
 482                 String containing the USB interface device path.
 483
 484 What:           /sys/bus/usb/devices/usbX/manufacturer
 485 Description:
 486                 Vendor specific string containing the name of the
 487                 manufacturer of the device.
 488
 489 What:           /sys/bus/usb/devices/usbX/maxchild
 490 Description:
 491                 Number of ports of an USB hub
 492
 493 What:           /sys/bus/usb/devices/usbX/persist
 494 Description:
 495                 Keeps the device even if it gets disconnected.
 496
 497 What:           /sys/bus/usb/devices/usbX/product
 498 Description:
 499                 Vendor specific string containing the name of the
 500                 device's product.
 501
 502 What:           /sys/bus/usb/devices/usbX/speed
 503 Description:
 504                 Shows the device's max speed, according to the USB version,
 505                 in Mbps.
 506                 Can be:
 507
 508                         =======         ====================
 509                         Unknown         speed unknown
 510                         1.5             Low speed
 511                         15              Full speed
 512                         480             High Speed
 513                         5000            Super Speed
 514                         10000           Super Speed+
 515                         20000           Super Speed+ Gen 2x2
 516                         =======         ====================
 517
 518 What:           /sys/bus/usb/devices/usbX/supports_autosuspend
 519 Description:
 520                 Returns 1 if the device doesn't support autosuspend.
 521                 Otherwise, returns 0.
 522
 523 What:           /sys/bus/usb/devices/usbX/urbnum
 524 Description:
 525                 Number of URBs submitted for the whole device.
 526
 527 What:           /sys/bus/usb/devices/usbX/version
 528 Description:
 529                 String containing the USB device version, as encoded
 530                 at the BCD descriptor.
 531
 532 What:           /sys/bus/usb/devices/usbX/power/autosuspend
 533 Description:
 534                 Time in milliseconds for the device to autosuspend. If the
 535                 value is negative, then autosuspend is prevented.
 536
 537                 (read/write)
 538
 539 What:           /sys/bus/usb/devices/usbX/power/active_duration
 540 Description:
 541                 The total time the device has not been suspended.
 542
 543 What:           /sys/bus/usb/devices/usbX/power/connected_duration
 544 Description:
 545                 The total time (in msec) that the device has been connected.
 546
 547 What:           /sys/bus/usb/devices/usbX/power/level
 548 Description:
 549
 550 What:           /sys/bus/usb/devices/usbX/ep_<N>/bEndpointAddress
 551 Description:
 552                 The address of the endpoint described by this descriptor,
 553                 in hexadecimal. The endpoint direction on this bitmapped field
 554                 is also shown at:
 555
 556                         /sys/bus/usb/devices/usbX/ep_<N>/direction
 557
 558                 See USB specs for its meaning.
 559
 560 What:           /sys/bus/usb/devices/usbX/ep_<N>/bInterval
 561 Description:
 562                 The interval of the endpoint as described on its descriptor,
 563                 in hexadecimal. The actual interval depends on the version
 564                 of the USB. Also shown in time units at
 565                 /sys/bus/usb/devices/usbX/ep_<N>/interval.
 566
 567 What:           /sys/bus/usb/devices/usbX/ep_<N>/bLength
 568 Description:
 569                 Number of bytes of the endpoint descriptor, in hexadecimal.
 570
 571 What:           /sys/bus/usb/devices/usbX/ep_<N>/bmAttributes
 572 Description:
 573                 Attributes which apply to the endpoint as described on its
 574                 descriptor, in hexadecimal. The endpoint type on this
 575                 bitmapped field is also shown at:
 576
 577                         /sys/bus/usb/devices/usbX/ep_<N>/type
 578
 579                 See USB specs for its meaning.
 580
 581 What:           /sys/bus/usb/devices/usbX/ep_<N>/direction
 582 Description:
 583                 Direction of the endpoint. Can be:
 584
 585                     - both (on control endpoints)
 586                     - in
 587                     - out
 588
 589 What:           /sys/bus/usb/devices/usbX/ep_<N>/interval
 590 Description:
 591                 Interval for polling endpoint for data transfers, in
 592                 milisseconds or microseconds.
 593
 594 What:           /sys/bus/usb/devices/usbX/ep_<N>/type
 595 Description:
 596                 Descriptor type. Can be:
 597
 598                     - Control
 599                     - Isoc
 600                     - Bulk
 601                     - Interrupt
 602                     - unknown
 603
 604 What:           /sys/bus/usb/devices/usbX/ep_<N>/wMaxPacketSize
 605 Description:
 606                 Maximum packet size this endpoint is capable of
 607                 sending or receiving, in hexadecimal.