summaryrefslogtreecommitdiffstats
path: root/kernel/Documentation/usb/power-management.txt
diff options
context:
space:
mode:
Diffstat (limited to 'kernel/Documentation/usb/power-management.txt')
-rw-r--r--kernel/Documentation/usb/power-management.txt16
1 files changed, 14 insertions, 2 deletions
diff --git a/kernel/Documentation/usb/power-management.txt b/kernel/Documentation/usb/power-management.txt
index b5f839117..0a94ffe17 100644
--- 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
----------------------