These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / Documentation / usb / power-management.txt

diff --git a/kernel/Documentation/usb/power-management.txt b/kernel/Documentation/usb/power-management.txt
index b5f8391..0a94ffe 100644 (file)
--- a/kernel/Documentation/usb/power-management.txt
+++ b/kernel/Documentation/usb/power-management.txt
@@ -521,10 +521,10 @@ enabling hardware LPM, the host can automatically put the device into
 lower power state(L1 for usb2.0 devices, or U1/U2 for usb3.0 devices),
 which state device can enter and resume very quickly.
 
-The user interface for controlling USB2 hardware LPM is located in the
+The user interface for controlling hardware LPM is located in the
 power/ subdirectory of each USB device's sysfs directory, that is, in
 /sys/bus/usb/devices/.../power/ where "..." is the device's ID. The
-relevant attribute files is usb2_hardware_lpm.
+relevant attribute files are usb2_hardware_lpm and usb3_hardware_lpm.
 
        power/usb2_hardware_lpm
 
@@ -537,6 +537,18 @@ relevant attribute files is usb2_hardware_lpm.
                can write y/Y/1 or n/N/0 to the file to enable/disable
                USB2 hardware LPM manually. This is for test purpose mainly.
 
+       power/usb3_hardware_lpm_u1
+       power/usb3_hardware_lpm_u2
+
+               When a USB 3.0 lpm-capable device is plugged in to a
+               xHCI host which supports link PM, it will check if U1
+               and U2 exit latencies have been set in the BOS
+               descriptor; if the check is is passed and the host
+               supports USB3 hardware LPM, USB3 hardware LPM will be
+               enabled for the device and these files will be created.
+               The files hold a string value (enable or disable)
+               indicating whether or not USB3 hardware LPM U1 or U2
+               is enabled for the device.
 
        USB Port Power Control
        ----------------------