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| author | Sarah Sharp <sarah.a.sharp@intel.com> | 2008-01-17 21:24:38 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-02-02 01:35:00 +0300 |
| commit | 979e524a9c563376af096d2d8629b9969fc06659 (patch) | |
| tree | 3401e794419fd257a2ed045b085e79f15b9d590e /Documentation/ABI/testing/sysfs-bus-usb | |
| parent | 1512300689426cb98bfd7e567ee9fdfaaf61b7c7 (diff) | |
| download | linux-979e524a9c563376af096d2d8629b9969fc06659.tar.xz | |
USB: Add documentation for USB suspend statistics.
This documents two newly created files:
/sys/bus/usb/device/.../power/connected_duration
/sys/bus/usb/device/.../power/active_duration
Documentation was placed in Documentation/ABI/testing, since that's where the
documentation is for the other USB sysfs power files.
Signed-off-by: Sarah Sharp <sarah.a.sharp@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation/ABI/testing/sysfs-bus-usb')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 9734577d1711..11a3c1682cec 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -52,3 +52,36 @@ Description: facility is inherently dangerous, it is disabled by default for all devices except hubs. For more information, see Documentation/usb/persist.txt. + +What: /sys/bus/usb/device/.../power/connected_duration +Date: January 2008 +KernelVersion: 2.6.25 +Contact: Sarah Sharp <sarah.a.sharp@intel.com> +Description: + If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file + is present. When read, it returns the total time (in msec) + that the USB device has been connected to the machine. This + file is read-only. +Users: + PowerTOP <power@bughost.org> + http://www.lesswatts.org/projects/powertop/ + +What: /sys/bus/usb/device/.../power/active_duration +Date: January 2008 +KernelVersion: 2.6.25 +Contact: Sarah Sharp <sarah.a.sharp@intel.com> +Description: + If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file + is present. When read, it returns the total time (in msec) + that the USB device has been active, i.e. not in a suspended + state. This file is read-only. + + Tools can use this file and the connected_duration file to + compute the percentage of time that a device has been active. + For example, + echo $((100 * `cat active_duration` / `cat connected_duration`)) + will give an integer percentage. Note that this does not + account for counter wrap. +Users: + PowerTOP <power@bughost.org> + http://www.lesswatts.org/projects/powertop/ |