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authorMathias Nyman <mathias.nyman@linux.intel.com>2013-05-23 17:14:31 +0300
committerSarah Sharp <sarah.a.sharp@linux.intel.com>2013-06-05 16:48:40 -0700
commit17f34867e98d2fb0c03918faab79efb989fa134b (patch)
tree1ea3f266473f6d6aa7fec9a646e04158941d0a06 /Documentation/ABI
parenta558ccdcc71c7770c5e80c926a31cfe8a3892a09 (diff)
downloadlinux-next-17f34867e98d2fb0c03918faab79efb989fa134b.tar.gz
usb: add usb2 Link PM variables to sysfs and usb_device
Adds abitilty to tune L1 timeout (inactivity timer for usb2 link sleep) and BESL (best effort service latency)via sysfs. This also adds a new usb2_lpm_parameters structure with those variables to struct usb_device. Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb27
1 files changed, 27 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index f093e59cbe5f..9759b8c91332 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -236,3 +236,30 @@ Description:
This attribute is to expose these information to user space.
The file will read "hotplug", "wired" and "not used" if the
information is available, and "unknown" otherwise.
+
+What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
+Date: May 2013
+Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
+Description:
+ USB 2.0 devices may support hardware link power management (LPM)
+ L1 sleep state. The usb2_lpm_l1_timeout attribute allows
+ tuning the timeout for L1 inactivity timer (LPM timer), e.g.
+ needed inactivity time before host requests the device to go to L1 sleep.
+ Useful for power management tuning.
+ Supported values are 0 - 65535 microseconds.
+
+What: /sys/bus/usb/devices/.../power/usb2_lpm_besl
+Date: May 2013
+Contact: Mathias Nyman <mathias.nyman@linux.intel.com>
+Description:
+ USB 2.0 devices that support hardware link power management (LPM)
+ L1 sleep state now use a best effort service latency value (BESL) to
+ indicate the best effort to resumption of service to the device after the
+ initiation of the resume event.
+ If the device does not have a preferred besl value then the host can select
+ one instead. This usb2_lpm_besl attribute allows to tune the host selected besl
+ value in order to tune power saving and service latency.
+
+ 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)