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-rw-r--r--Documentation/ABI/testing/sysfs-bus-usb15
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 294aa864a60a..e647378e9e88 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -142,3 +142,18 @@ Description:
 		such devices.
 Users:
 		usb_modeswitch
+
+What:		/sys/bus/usb/devices/.../power/usb2_hardware_lpm
+Date:		September 2011
+Contact:	Andiry Xu <andiry.xu@amd.com>
+Description:
+		If CONFIG_USB_SUSPEND is set and a USB 2.0 lpm-capable device
+		is plugged in to a xHCI host which support link PM, it will
+		perform a LPM test; if the test is passed and host supports
+		USB2 hardware LPM (xHCI 1.0 feature), USB2 hardware LPM will
+		be enabled for the device and the USB device directory will
+		contain a file named power/usb2_hardware_lpm.  The file holds
+		a string value (enable or disable) indicating whether or not
+		USB2 hardware LPM is enabled for the device. Developer can
+		write y/Y/1 or n/N/0 to the file to enable/disable the
+		feature.