From 024f117c2f3c4bb5df6e6696b709e0f3ed7e5dbb Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Thu, 5 Jul 2012 17:17:24 -0700 Subject: USB: Add a sysfs file to show LTM capabilities. USB 3.0 devices can optionally support Latency Tolerance Messaging (LTM). Add a new sysfs file in the device directory to show whether a device is LTM capable. This file will be present for both USB 2.0 and USB 3.0 devices. Signed-off-by: Sarah Sharp --- Documentation/ABI/testing/sysfs-bus-usb | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 6df4e6f57560..5f75f8f7df34 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -208,3 +208,15 @@ Description: such as ACPI. This file will read either "removable" or "fixed" if the information is available, and "unknown" otherwise. + +What: /sys/bus/usb/devices/.../ltm_capable +Date: July 2012 +Contact: Sarah Sharp +Description: + USB 3.0 devices may optionally support Latency Tolerance + Messaging (LTM). They indicate their support by setting a bit + in the bmAttributes field of their SuperSpeed BOS descriptors. + If that bit is set for the device, ltm_capable will read "yes". + If the device doesn't support LTM, the file will read "no". + The file will be present for all speeds of USB devices, and will + always read "no" for USB 1.1 and USB 2.0 devices. -- cgit v1.2.3