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Documentation sysfs-bus-usb: Document all files used by libusb

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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hans de Goede 2013-08-14 15:34:27 +02:00 committed by Greg Kroah-Hartman
parent bb67490711
commit da9651a5d3
1 changed files with 38 additions and 0 deletions
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38
Documentation/ABI/testing/sysfs-bus-usb
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@ -263,3 +263,41 @@ Description:
Supported values are 0 - 15.
More information on how besl values map to microseconds can be found in
USB 2.0 ECN Errata for Link Power Management, section 4.10)
What: /sys/bus/usb/devices/.../devnum
KernelVersion: since at least 2.6.18
Description:
Device address on the USB bus.
What: /sys/bus/usb/devices/.../bConfigurationValue
KernelVersion: since at least 2.6.18
Description:
bConfigurationValue of the *active* configuration for the
device. Writing 0 or -1 to bConfigurationValue will reset the
active configuration (unconfigure the device). Writing
another value will change the active configuration.
Note that some devices, in violation of the USB spec, have a
configuration with a value equal to 0. Writing 0 to
bConfigurationValue for these devices will install that
configuration, rather then unconfigure the device.
Writing -1 will always unconfigure the device.
What: /sys/bus/usb/devices/.../busnum
KernelVersion: 2.6.22
Description:
Bus-number of the USB-bus the device is connected to.
What: /sys/bus/usb/devices/.../descriptors
KernelVersion: 2.6.26
Description:
Binary file containing cached descriptors of the device. The
binary data consists of the device descriptor followed by the
descriptors for each configuration of the device.
Note that the wTotalLength of the config descriptors can not
be trusted, as the device may have a smaller config descriptor
than it advertises. The bLength field of each (sub) descriptor
can be trusted, and can be used to seek forward one (sub)
descriptor at a time until the next config descriptor is found.
All descriptors read from this file are in bus-endian format