linux.git/drivers/base/power/wakeup.c, branch v3.7

PM / wakeup: Use irqsave/irqrestore for events_lock

2012-09-06T21:19:06+00:00

Jon Medhurst (Tixy) recently noticed a problem with the
events_lock usage. One of the Android patches that uses
wakeup_sources calls wakeup_source_add() with irqs disabled.
However, the event_lock usage in wakeup_source_add() uses
spin_lock_irq()/spin_unlock_irq(), which reenables interrupts.
This results in lockdep warnings.

The fix is to use spin_lock_irqsave()/spin_lock_irqrestore()
instead for the events_lock.

References: https://bugs.launchpad.net/linaro-landing-team-arm/+bug/1037565
Reported-and-debugged-by: Jon Medhurst (Tixy) 
Signed-off-by: John Stultz 
Signed-off-by: Rafael J. Wysocki

PM / Sleep: Print name of wakeup source that aborts suspend

2012-08-17T17:40:50+00:00

A driver or app may repeatedly request a wakeup source while the system
is attempting to enter suspend, which may indicate a bug or at least
point out a highly active system component that is responsible for
decreased battery life on a mobile device.  Even when the incidence
of suspend abort is not severe, identifying wakeup sources that
frequently abort suspend can be a useful clue for power management
analysis.

In some cases the existing stats can point out the offender where there is
an unexpectedly high activation count that stands out from the others, but
in other cases the wakeup source frequently taken just after the rest of
the system thinks its time to suspend might not stand out in the overall
stats.

It is also often useful to have information about what's been happening
recently, rather than totals of all activity for the system boot.

It's suggested to dump a line about which wakeup source
aborted suspend to aid analysis of these situations.

Signed-off-by: Todd Poynor 
Signed-off-by: Rafael J. Wysocki

PM / Sleep: Add user space interface for manipulating wakeup sources, v3

2012-05-01T19:26:05+00:00

Android allows user space to manipulate wakelocks using two
sysfs file located in /sys/power/, wake_lock and wake_unlock.
Writing a wakelock name and optionally a timeout to the wake_lock
file causes the wakelock whose name was written to be acquired (it
is created before is necessary), optionally with the given timeout.
Writing the name of a wakelock to wake_unlock causes that wakelock
to be released.

Implement an analogous interface for user space using wakeup sources.
Add the /sys/power/wake_lock and /sys/power/wake_unlock files
allowing user space to create, activate and deactivate wakeup
sources, such that writing a name and optionally a timeout to
wake_lock causes the wakeup source of that name to be activated,
optionally with the given timeout.  If that wakeup source doesn't
exist, it will be created and then activated.  Writing a name to
wake_unlock causes the wakeup source of that name, if there is one,
to be deactivated.  Wakeup sources created with the help of
wake_lock that haven't been used for more than 5 minutes are garbage
collected and destroyed.  Moreover, there can be only WL_NUMBER_LIMIT
wakeup sources created with the help of wake_lock present at a time.

The data type used to track wakeup sources created by user space is
called "struct wakelock" to indicate the origins of this feature.

This version of the patch includes an rbtree manipulation fix from John Stultz.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman 
Reviewed-by: NeilBrown

PM / Sleep: Add "prevent autosleep time" statistics to wakeup sources

2012-05-01T19:25:49+00:00

Android uses one wakelock statistics that is only necessary for
opportunistic sleep.  Namely, the prevent_suspend_time field
accumulates the total time the given wakelock has been locked
while "automatic suspend" was enabled.  Add an analogous field,
prevent_sleep_time, to wakeup sources and make it behave in a similar
way.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman

PM / Sleep: Implement opportunistic sleep, v2

2012-05-01T19:25:38+00:00

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 
Acked-by: Greg Kroah-Hartman 
Reviewed-by: NeilBrown

PM / Sleep: Add wakeup_source_activate and wakeup_source_deactivate tracepoints

2012-05-01T19:25:25+00:00

Add tracepoints to wakeup_source_activate and wakeup_source_deactivate.
Useful for checking that specific wakeup sources overlap as expected.

Signed-off-by: Arve Hjønnevåg 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Rafael J. Wysocki

PM / Sleep: Change wakeup source statistics to follow Android

2012-05-01T19:25:11+00:00

Wakeup statistics used by Android are slightly different from what we
have in wakeup sources at the moment and there aren't any known
users of those statistics other than Android, so modify them to make
it easier for Android to switch to wakeup sources.

This removes the struct wakeup_source's hit_cout field, which is very
rough and therefore not very useful, and adds two new fields,
wakeup_count and expire_count.  The first one tracks how many times
the wakeup source is activated with events_check_enabled set (which
roughly corresponds to the situations when a system power transition
to a sleep state is in progress and would be aborted by this wakeup
source if it were the only active one at that time) and the second
one is the number of times the wakeup source has been activated with
a timeout that expired.

Additionally, the last_time field is now updated when the wakeup
source is deactivated too (previously it was only updated during
the wakeup source's activation), which seems to be what Android does
with the analogous counter for wakelocks.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman

PM / Sleep: Use wait queue to signal "no wakeup events in progress"

2012-05-01T19:24:59+00:00

The current wakeup source deactivation code doesn't do anything when
the counter of wakeup events in progress goes down to zero, which
requires pm_get_wakeup_count() to poll that counter periodically.
Although this reduces the average time it takes to deactivate a
wakeup source, it also may lead to a substantial amount of unnecessary
polling if there are extended periods of wakeup activity.  Thus it
seems reasonable to use a wait queue for signaling the "no wakeup
events in progress" condition and remove the polling.

Signed-off-by: Rafael J. Wysocki 
Acked-by: mark gross 
Acked-by: Greg Kroah-Hartman

PM / Sleep: Add more wakeup source initialization routines

2012-03-04T22:08:46+00:00

The existing wakeup source initialization routines are not
particularly useful for wakeup sources that aren't created by
wakeup_source_create(), because their users have to open code
filling the objects with zeros and setting their names.  For this
reason, introduce routines that can be used for initializing, for
example, static wakeup source objects.

Requested-by: Arve Hjønnevåg 
Signed-off-by: Rafael J. Wysocki

PM / Sleep: Make __pm_stay_awake() delete wakeup source timers

2012-03-04T22:08:27+00:00

If __pm_stay_awake() is called after __pm_wakeup_event() for the same
wakep source object before its timer expires, it won't cancel the
timer, so the wakeup source will be deactivated from the timer
function as scheduled by __pm_wakeup_event().  In that case
__pm_stay_awake() doesn't have any effect beyond incrementing
the wakeup source's event_count field, although it should cancel
the timer and make the wakeup source stay active until __pm_relax()
is called for it.

To fix this problem make __pm_stay_awake() delete the wakeup source's
timer and ensure that it won't be deactivated from the timer funtion
afterwards by clearing its timer_expires field.

Reported-by: Arve Hjønnevåg 
Signed-off-by: Rafael J. Wysocki