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Currently, the USB hub core waits for 50 ms after enumerating the
device. This was added to help "some high speed devices" to
enumerate (b789696af8 "[PATCH] USB: relax usbcore reset timings").
On some devices, the time-to-active is important, so we provide
a per-port option to reduce the time to what the USB specification
requires: 10 ms.
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
279 lines
11 KiB
Plaintext
279 lines
11 KiB
Plaintext
What: /sys/bus/usb/devices/INTERFACE/authorized
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Date: August 2015
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Description:
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This allows to authorize (1) or deauthorize (0)
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individual interfaces instead a whole device
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in contrast to the device authorization.
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If a deauthorized interface will be authorized
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so the driver probing must be triggered manually
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by writing INTERFACE to /sys/bus/usb/drivers_probe
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This allows to avoid side-effects with drivers
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that need multiple interfaces.
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A deauthorized interface cannot be probed or claimed.
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What: /sys/bus/usb/devices/usbX/interface_authorized_default
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Date: August 2015
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Description:
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This is used as value that determines if interfaces
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would be authorized by default.
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The value can be 1 or 0. It's by default 1.
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What: /sys/bus/usb/device/.../authorized
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Date: July 2008
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KernelVersion: 2.6.26
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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Authorized devices are available for use by device
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drivers, non-authorized one are not. By default, wired
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USB devices are authorized.
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Certified Wireless USB devices are not authorized
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initially and should be (by writing 1) after the
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device has been authenticated.
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What: /sys/bus/usb/device/.../wusb_cdid
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Date: July 2008
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KernelVersion: 2.6.27
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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For Certified Wireless USB devices only.
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A devices's CDID, as 16 space-separated hex octets.
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What: /sys/bus/usb/device/.../wusb_ck
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Date: July 2008
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KernelVersion: 2.6.27
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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For Certified Wireless USB devices only.
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Write the device's connection key (CK) to start the
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authentication of the device. The CK is 16
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space-separated hex octets.
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What: /sys/bus/usb/device/.../wusb_disconnect
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Date: July 2008
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KernelVersion: 2.6.27
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Contact: David Vrabel <david.vrabel@csr.com>
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Description:
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For Certified Wireless USB devices only.
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Write a 1 to force the device to disconnect
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(equivalent to unplugging a wired USB device).
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What: /sys/bus/usb/drivers/.../new_id
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Date: October 2011
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Contact: linux-usb@vger.kernel.org
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Description:
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Writing a device ID to this file will attempt to
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dynamically add a new device ID to a USB device driver.
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This may allow the driver to support more hardware than
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was included in the driver's static device ID support
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table at compile time. The format for the device ID is:
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idVendor idProduct bInterfaceClass RefIdVendor RefIdProduct
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The vendor ID and device ID fields are required, the
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rest is optional. The Ref* tuple can be used to tell the
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driver to use the same driver_data for the new device as
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it is used for the reference device.
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Upon successfully adding an ID, the driver will probe
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for the device and attempt to bind to it. For example:
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# echo "8086 10f5" > /sys/bus/usb/drivers/foo/new_id
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Here add a new device (0458:7045) using driver_data from
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an already supported device (0458:704c):
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# echo "0458 7045 0 0458 704c" > /sys/bus/usb/drivers/foo/new_id
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Reading from this file will list all dynamically added
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device IDs in the same format, with one entry per
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line. For example:
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# cat /sys/bus/usb/drivers/foo/new_id
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8086 10f5
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dead beef 06
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f00d cafe
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The list will be truncated at PAGE_SIZE bytes due to
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sysfs restrictions.
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What: /sys/bus/usb-serial/drivers/.../new_id
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Date: October 2011
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Contact: linux-usb@vger.kernel.org
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Description:
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For serial USB drivers, this attribute appears under the
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extra bus folder "usb-serial" in sysfs; apart from that
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difference, all descriptions from the entry
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"/sys/bus/usb/drivers/.../new_id" apply.
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What: /sys/bus/usb/drivers/.../remove_id
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Date: November 2009
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Contact: CHENG Renquan <rqcheng@smu.edu.sg>
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Description:
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Writing a device ID to this file will remove an ID
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that was dynamically added via the new_id sysfs entry.
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The format for the device ID is:
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idVendor idProduct. After successfully
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removing an ID, the driver will no longer support the
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device. This is useful to ensure auto probing won't
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match the driver to the device. For example:
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# echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
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Reading from this file will list the dynamically added
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device IDs, exactly like reading from the entry
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"/sys/bus/usb/drivers/.../new_id"
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What: /sys/bus/usb/devices/.../power/usb2_hardware_lpm
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Date: September 2011
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Contact: Andiry Xu <andiry.xu@amd.com>
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Description:
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If CONFIG_PM is set and a USB 2.0 lpm-capable device is plugged
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in to a xHCI host which support link PM, it will perform a LPM
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test; if the test is passed and host supports USB2 hardware LPM
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(xHCI 1.0 feature), USB2 hardware LPM will be enabled for the
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device and the USB device directory will contain a file named
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power/usb2_hardware_lpm. The file holds a string value (enable
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or disable) indicating whether or not USB2 hardware LPM is
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enabled for the device. Developer can write y/Y/1 or n/N/0 to
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the file to enable/disable the feature.
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What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm_u1
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/sys/bus/usb/devices/.../power/usb3_hardware_lpm_u2
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Date: November 2015
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Contact: Kevin Strasser <kevin.strasser@linux.intel.com>
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Lu Baolu <baolu.lu@linux.intel.com>
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Description:
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If CONFIG_PM is set and a USB 3.0 lpm-capable device is plugged
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in to a xHCI host which supports link PM, it will check if U1
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and U2 exit latencies have been set in the BOS descriptor; if
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the check is passed and the host supports USB3 hardware LPM,
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USB3 hardware LPM will be enabled for the device and the USB
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device directory will contain two files named
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power/usb3_hardware_lpm_u1 and power/usb3_hardware_lpm_u2. These
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files hold a string value (enable or disable) indicating whether
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or not USB3 hardware LPM U1 or U2 is enabled for the device.
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What: /sys/bus/usb/devices/.../removable
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Date: February 2012
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Contact: Matthew Garrett <mjg@redhat.com>
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Description:
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Some information about whether a given USB device is
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physically fixed to the platform can be inferred from a
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combination of hub descriptor bits and platform-specific data
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such as ACPI. This file will read either "removable" or
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"fixed" if the information is available, and "unknown"
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otherwise.
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What: /sys/bus/usb/devices/.../ltm_capable
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Date: July 2012
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Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com>
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Description:
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USB 3.0 devices may optionally support Latency Tolerance
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Messaging (LTM). They indicate their support by setting a bit
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in the bmAttributes field of their SuperSpeed BOS descriptors.
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If that bit is set for the device, ltm_capable will read "yes".
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If the device doesn't support LTM, the file will read "no".
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The file will be present for all speeds of USB devices, and will
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always read "no" for USB 1.1 and USB 2.0 devices.
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What: /sys/bus/usb/devices/.../(hub interface)/portX
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Date: August 2012
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Contact: Lan Tianyu <tianyu.lan@intel.com>
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Description:
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The /sys/bus/usb/devices/.../(hub interface)/portX
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is usb port device's sysfs directory.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/connect_type
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Date: January 2013
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Contact: Lan Tianyu <tianyu.lan@intel.com>
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Description:
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Some platforms provide usb port connect types through ACPI.
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This attribute is to expose these information to user space.
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The file will read "hotplug", "wired" and "not used" if the
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information is available, and "unknown" otherwise.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/quirks
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Date: May 2018
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Contact: Nicolas Boichat <drinkcat@chromium.org>
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Description:
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In some cases, we care about time-to-active for devices
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connected on a specific port (e.g. non-standard USB port like
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pogo pins), where the device to be connected is known in
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advance, and behaves well according to the specification.
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This attribute is a bit-field that controls the behavior of
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a specific port:
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- Bit 0 of this field selects the "old" enumeration scheme,
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as it is considerably faster (it only causes one USB reset
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instead of 2).
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The old enumeration scheme can also be selected globally
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using /sys/module/usbcore/parameters/old_scheme_first, but
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it is often not desirable as the new scheme was introduced to
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increase compatibility with more devices.
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- Bit 1 reduces TRSTRCY to the 10 ms that are required by the
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USB 2.0 specification, instead of the 50 ms that are normally
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used to help make enumeration work better on some high speed
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devices.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count
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Date: February 2018
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Contact: Richard Leitner <richard.leitner@skidata.com>
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Description:
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Most hubs are able to detect over-current situations on their
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ports and report them to the kernel. This attribute is to expose
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the number of over-current situation occurred on a specific port
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to user space. This file will contain an unsigned 32 bit value
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which wraps to 0 after its maximum is reached.
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What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
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Date: November 2015
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Contact: Lu Baolu <baolu.lu@linux.intel.com>
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Description:
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Some USB3.0 devices are not friendly to USB3 LPM. usb3_lpm_permit
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attribute allows enabling/disabling usb3 lpm of a port. It takes
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effect both before and after a usb device is enumerated. Supported
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values are "0" if both u1 and u2 are NOT permitted, "u1" if only u1
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is permitted, "u2" if only u2 is permitted, "u1_u2" if both u1 and
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u2 are permitted.
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What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
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Date: May 2013
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Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
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Description:
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USB 2.0 devices may support hardware link power management (LPM)
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L1 sleep state. The usb2_lpm_l1_timeout attribute allows
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tuning the timeout for L1 inactivity timer (LPM timer), e.g.
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needed inactivity time before host requests the device to go to L1 sleep.
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Useful for power management tuning.
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Supported values are 0 - 65535 microseconds.
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What: /sys/bus/usb/devices/.../power/usb2_lpm_besl
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Date: May 2013
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Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
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Description:
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USB 2.0 devices that support hardware link power management (LPM)
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L1 sleep state now use a best effort service latency value (BESL) to
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indicate the best effort to resumption of service to the device after the
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initiation of the resume event.
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If the device does not have a preferred besl value then the host can select
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one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
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value in order to tune power saving and service latency.
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Supported values are 0 - 15.
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More information on how besl values map to microseconds can be found in
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USB 2.0 ECN Errata for Link Power Management, section 4.10)
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What: /sys/bus/usb/devices/.../rx_lanes
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Date: March 2018
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Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
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Description:
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Number of rx lanes the device is using.
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USB 3.2 adds Dual-lane support, 2 rx and 2 tx lanes over Type-C.
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Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per
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direction. Devices before USB 3.2 are single lane (rx_lanes = 1)
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What: /sys/bus/usb/devices/.../tx_lanes
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Date: March 2018
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Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
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Description:
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Number of tx lanes the device is using.
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USB 3.2 adds Dual-lane support, 2 rx and 2 tx -lanes over Type-C.
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Inter-Chip SSIC devices support asymmetric lanes up to 4 lanes per
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direction. Devices before USB 3.2 are single lane (tx_lanes = 1)
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