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-rw-r--r--Documentation/power/runtime_pm.txt19
1 files changed, 13 insertions, 6 deletions
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 64546eb9a16a..ee69d7532172 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -478,15 +478,23 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
- set the power.last_busy field to the current time
void pm_runtime_use_autosuspend(struct device *dev);
- - set the power.use_autosuspend flag, enabling autosuspend delays
+ - set the power.use_autosuspend flag, enabling autosuspend delays; call
+ pm_runtime_get_sync if the flag was previously cleared and
+ power.autosuspend_delay is negative
void pm_runtime_dont_use_autosuspend(struct device *dev);
- - clear the power.use_autosuspend flag, disabling autosuspend delays
+ - clear the power.use_autosuspend flag, disabling autosuspend delays;
+ decrement the device's usage counter if the flag was previously set and
+ power.autosuspend_delay is negative; call pm_runtime_idle
void pm_runtime_set_autosuspend_delay(struct device *dev, int delay);
- set the power.autosuspend_delay value to 'delay' (expressed in
milliseconds); if 'delay' is negative then runtime suspends are
- prevented
+ prevented; if power.use_autosuspend is set, pm_runtime_get_sync may be
+ called or the device's usage counter may be decremented and
+ pm_runtime_idle called depending on if power.autosuspend_delay is
+ changed to or from a negative value; if power.use_autosuspend is clear,
+ pm_runtime_idle is called
unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
- calculate the time when the current autosuspend delay period will expire,
@@ -836,9 +844,8 @@ of the non-autosuspend counterparts:
Instead of: pm_runtime_put_sync use: pm_runtime_put_sync_autosuspend.
Drivers may also continue to use the non-autosuspend helper functions; they
-will behave normally, not taking the autosuspend delay into account.
-Similarly, if the power.use_autosuspend field isn't set then the autosuspend
-helper functions will behave just like the non-autosuspend counterparts.
+will behave normally, which means sometimes taking the autosuspend delay into
+account (see pm_runtime_idle).
Under some circumstances a driver or subsystem may want to prevent a device
from autosuspending immediately, even though the usage counter is zero and the