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authorSarah Sharp <sarah.a.sharp@linux.intel.com>2012-07-05 17:17:24 -0700
committerSarah Sharp <sarah.a.sharp@linux.intel.com>2012-07-11 07:06:48 -0400
commit024f117c2f3c4bb5df6e6696b709e0f3ed7e5dbb (patch)
tree3ad556877608c58bd7844f82810dfc0d471d4f63 /Documentation/ABI
parentf74631e3426474183389e55f703797bd965cd356 (diff)
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op-kernel-dev-024f117c2f3c4bb5df6e6696b709e0f3ed7e5dbb.tar.gz
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/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb12
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 6df4e6f..5f75f8f 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.
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