diff options
author | Sarah Sharp <sarah.a.sharp@intel.com> | 2008-01-17 13:24:38 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-02-01 17:35:00 -0500 |
commit | 979e524a9c563376af096d2d8629b9969fc06659 (patch) | |
tree | 3401e794419fd257a2ed045b085e79f15b9d590e /Documentation/ABI/testing/sysfs-bus-usb | |
parent | 1512300689426cb98bfd7e567ee9fdfaaf61b7c7 (diff) |
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: | |||
52 | facility is inherently dangerous, it is disabled by default | 52 | facility is inherently dangerous, it is disabled by default |
53 | for all devices except hubs. For more information, see | 53 | for all devices except hubs. For more information, see |
54 | Documentation/usb/persist.txt. | 54 | Documentation/usb/persist.txt. |
55 | |||
56 | What: /sys/bus/usb/device/.../power/connected_duration | ||
57 | Date: January 2008 | ||
58 | KernelVersion: 2.6.25 | ||
59 | Contact: Sarah Sharp <sarah.a.sharp@intel.com> | ||
60 | Description: | ||
61 | If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file | ||
62 | is present. When read, it returns the total time (in msec) | ||
63 | that the USB device has been connected to the machine. This | ||
64 | file is read-only. | ||
65 | Users: | ||
66 | PowerTOP <power@bughost.org> | ||
67 | http://www.lesswatts.org/projects/powertop/ | ||
68 | |||
69 | What: /sys/bus/usb/device/.../power/active_duration | ||
70 | Date: January 2008 | ||
71 | KernelVersion: 2.6.25 | ||
72 | Contact: Sarah Sharp <sarah.a.sharp@intel.com> | ||
73 | Description: | ||
74 | If CONFIG_PM and CONFIG_USB_SUSPEND are enabled, then this file | ||
75 | is present. When read, it returns the total time (in msec) | ||
76 | that the USB device has been active, i.e. not in a suspended | ||
77 | state. This file is read-only. | ||
78 | |||
79 | Tools can use this file and the connected_duration file to | ||
80 | compute the percentage of time that a device has been active. | ||
81 | For example, | ||
82 | echo $((100 * `cat active_duration` / `cat connected_duration`)) | ||
83 | will give an integer percentage. Note that this does not | ||
84 | account for counter wrap. | ||
85 | Users: | ||
86 | PowerTOP <power@bughost.org> | ||
87 | http://www.lesswatts.org/projects/powertop/ | ||