diff options
| author | Sarah Sharp <sarah.a.sharp@linux.intel.com> | 2012-07-05 17:17:24 -0700 |
|---|---|---|
| committer | Sarah Sharp <sarah.a.sharp@linux.intel.com> | 2012-07-11 07:06:48 -0400 |
| commit | 024f117c2f3c4bb5df6e6696b709e0f3ed7e5dbb (patch) | |
| tree | 3ad556877608c58bd7844f82810dfc0d471d4f63 /Documentation | |
| parent | f74631e3426474183389e55f703797bd965cd356 (diff) | |
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 <sarah.a.sharp@linux.intel.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 6df4e6f5756..5f75f8f7df3 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 <sarah.a.sharp@linux.intel.com> +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. |