USB: Export suspend statistics
commit1512300689426cb98bfd7e567ee9fdfaaf61b7c7
authorSarah Sharp <saharabeara@gmail.com>
Sat, 22 Dec 2007 00:54:15 +0000 (21 16:54 -0800)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 1 Feb 2008 22:35:00 +0000 (1 14:35 -0800)
treea275493675fe7bc6b666d1c6a8179e103c7a199c
parent228426edac844a2c9270528e9cd7ab6260ef7628
USB: Export suspend statistics

This patch exports two statistics to userspace:
/sys/bus/usb/device/.../power/connected_duration
/sys/bus/usb/device/.../power/active_duration

connected_duration is the total time (in msec) that the device has
been connected.  active_duration is the total time the device has not
been suspended.  With these two statistics, tools like PowerTOP can
calculate the percentage time that a device is active, i.e. not
suspended or auto-suspended.

Users can also use the active_duration to check if a device is actually
autosuspended.  Currently, they can set power/level to auto and
power/autosuspend to a positive timeout, but there's no way to know from
userspace if a device was actually autosuspended without looking at the
dmesg output.  These statistics will be useful in creating an automated
userspace script to test autosuspend for USB devices.

Signed-off-by: Sarah Sharp <sarah.a.sharp@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/usb/core/hub.c
drivers/usb/core/sysfs.c
drivers/usb/core/usb.c
include/linux/usb.h