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usbcore: add sysfs support to xHCI usb3 hardware LPM

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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>
This commit is contained in:
Kevin Strasser
2015-06-16 10:35:30 -07:00
committed by Greg Kroah-Hartman
parent eb4861c3ce
commit 655fe4effe
4 changed files with 62 additions and 2 deletions
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14
Documentation/ABI/testing/sysfs-bus-usb
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@@ -114,6 +114,20 @@ Description:
enabled for the device. Developer can write y/Y/1 or n/N/0 to
the file to enable/disable the feature.
What: /sys/bus/usb/devices/.../power/usb3_hardware_lpm
Date: June 2015
Contact: Kevin Strasser <kevin.strasser@linux.intel.com>
Description:
If CONFIG_PM_RUNTIME is set and 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 the USB device directory will contain a file named
power/usb3_hardware_lpm. The file holds a string value (enable
or disable) indicating whether or not USB3 hardware LPM is
enabled for the device.
What: /sys/bus/usb/devices/.../removable
Date: February 2012
Contact: Matthew Garrett <mjg@redhat.com>