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70f400d4d9
Move the "removable" attribute from USB to core in order to allow it to be
supported by other subsystem / buses. Individual buses that want to support
this attribute can populate the removable property of the device while
enumerating it with the 3 possible values -
- "unknown"
- "fixed"
- "removable"
Leaving the field unchanged (i.e. "not supported") would mean that the
attribute would not show up in sysfs for that device. The UAPI (location,
symantics etc) for the attribute remains unchanged.
Move the "removable" attribute from USB to the device core so it can be
used by other subsystems / buses.
By default, devices do not have a "removable" attribute in sysfs.
If a subsystem or bus driver wants to support a "removable" attribute, it
should call device_set_removable() before calling device_register() or
device_add(), e.g.:
device_set_removable(dev, DEVICE_REMOVABLE);
device_register(dev);
The possible values and the resulting sysfs attribute contents are:
DEVICE_REMOVABLE_UNKNOWN -> "unknown"
DEVICE_REMOVABLE -> "removable"
DEVICE_FIXED -> "fixed"
Convert the USB "removable" attribute to use this new device core
functionality. There should be no user-visible change in the location or
semantics of attribute for USB devices.
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rajat Jain <rajatja@google.com>
Link: https://lore.kernel.org/r/20210524171812.18095-1-rajatja@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
291 lines
11 KiB
Plaintext
291 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/.../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", "hardwired" 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/location
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Date: October 2018
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Contact: Bjørn Mork <bjorn@mork.no>
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Description:
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Some platforms provide usb port physical location through
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firmware. This is used by the kernel to pair up logical ports
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mapping to the same physical connector. The attribute exposes the
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raw location value as a hex integer.
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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. This file supports
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poll() for monitoring changes to this value in user space.
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Any time this value changes the corresponding hub device will send a
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udev event with the following attributes::
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OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX
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OVER_CURRENT_COUNT=[current value of this sysfs attribute]
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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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