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authorJohan Hovold <johan@kernel.org>2017-04-10 13:38:25 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-04-19 23:29:18 +0200
commitbafdcde73be7d462129cecfc339d3a6abcba91d2 (patch)
tree397c5bb357399f8d38236d9fde77ed856a2f0dac /Documentation
parent72ec2e17f9f7f7f6082ec57183080726eb3523e3 (diff)
PM / runtime: Document autosuspend-helper side effects
Document the fact that the autosuspend delay and enable helpers may change the power.usage_count and resume or suspend a device depending on the values of power.autosuspend_delay and power.use_autosuspend. Note that this means that a driver must disable autosuspend before disabling runtime pm on probe errors and on driver unbind if the device is to be suspended upon return (as a negative delay may otherwise keep the device resumed). Signed-off-by: Johan Hovold <johan@kernel.org> Acked-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/power/runtime_pm.txt14
1 files changed, 11 insertions, 3 deletions
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 56a13b865927..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,