diff options
| author | Kevin Strasser <kevin.strasser@linux.intel.com> | 2015-06-16 10:35:30 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-07-22 15:45:03 -0700 |
| commit | 655fe4effe0f1f40e4f6ca6b3cc64a7fe0032183 (patch) | |
| tree | 00e7be3af68a08b25e6688fc8d4571124b81d704 /Documentation/usb | |
| parent | eb4861c3cef7f745df0d2a26b0f4287da0190424 (diff) | |
usbcore: add sysfs support to xHCI usb3 hardware LPM
Add a sysfs node to make it easier to verify if LPM is supported and being
enabled for USB 3.0 devices.
Signed-off-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/usb')
| -rw-r--r-- | Documentation/usb/power-management.txt | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/Documentation/usb/power-management.txt b/Documentation/usb/power-management.txt index b5f83911732a..4a15c90bc11d 100644 --- a/Documentation/usb/power-management.txt +++ b/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 +537,17 @@ 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 + + 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 this file will be created. + The file holds a string value (enable or disable) + indicating whether or not USB3 hardware LPM is + enabled for the device. USB Port Power Control ---------------------- |