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| author | Rafael J. Wysocki <rjw@sisk.pl> | 2012-04-29 22:53:22 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rjw@sisk.pl> | 2012-05-01 21:25:38 +0200 |
| commit | 7483b4a4d9abf9dcf1ffe6e805ead2847ec3264e (patch) | |
| tree | d03af746dc3be6480580ec569e0c2d708031f0bd /Documentation/ABI | |
| parent | 6791e36c4a40e8930e08669e60077eea6770c429 (diff) | |
| download | lwn-7483b4a4d9abf9dcf1ffe6e805ead2847ec3264e.tar.gz lwn-7483b4a4d9abf9dcf1ffe6e805ead2847ec3264e.zip | |
PM / Sleep: Implement opportunistic sleep, v2
Introduce a mechanism by which the kernel can trigger global
transitions to a sleep state chosen by user space if there are no
active wakeup sources.
It consists of a new sysfs attribute, /sys/power/autosleep, that
can be written one of the strings returned by reads from
/sys/power/state, an ordered workqueue and a work item carrying out
the "suspend" operations. If a string representing the system's
sleep state is written to /sys/power/autosleep, the work item
triggering transitions to that state is queued up and it requeues
itself after every execution until user space writes "off" to
/sys/power/autosleep.
That work item enables the detection of wakeup events using the
functions already defined in drivers/base/power/wakeup.c (with one
small modification) and calls either pm_suspend(), or hibernate() to
put the system into a sleep state. If a wakeup event is reported
while the transition is in progress, it will abort the transition and
the "system suspend" work item will be queued up again.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-power | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index b464d12761ba..237c735db6c9 100644 --- a/Documentation/ABI/testing/sysfs-power +++ b/Documentation/ABI/testing/sysfs-power @@ -172,3 +172,20 @@ Description: Reading from this file will display the current value, which is set to 1 MB by default. + +What: /sys/power/autosleep +Date: April 2012 +Contact: Rafael J. Wysocki <rjw@sisk.pl> +Description: + The /sys/power/autosleep file can be written one of the strings + returned by reads from /sys/power/state. If that happens, a + work item attempting to trigger a transition of the system to + the sleep state represented by that string is queued up. This + attempt will only succeed if there are no active wakeup sources + in the system at that time. After every execution, regardless + of whether or not the attempt to put the system to sleep has + succeeded, the work item requeues itself until user space + writes "off" to /sys/power/autosleep. + + Reading from this file causes the last string successfully + written to it to be returned. |