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PM / runtime: Add new helper for conditional usage count incrementation

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Introduce a new runtime PM function, pm_runtime_get_if_in_use(),
that will increment the device's runtime PM usage counter and
return 1 if its status is RPM_ACTIVE and its usage counter
is greater than 0 at the same time (0 will be returned otherwise).

This is useful for things that should only be done if the device
is active (from the runtime PM perspective) and used by somebody
(as indicated by the usage counter) already and they are not worth
bothering otherwise.

Requested-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki
2015-12-17 02:54:26 +01:00
parent d89d7ff9ed
commit a436b6a19f
3 changed files with 35 additions and 0 deletions
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24
drivers/base/power/runtime.c
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@@ -965,6 +965,30 @@ int __pm_runtime_resume(struct device *dev, int rpmflags)
}
EXPORT_SYMBOL_GPL(__pm_runtime_resume);
/**
* pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
* @dev: Device to handle.
*
* Return -EINVAL if runtime PM is disabled for the device.
*
* If that's not the case and if the device's runtime PM status is RPM_ACTIVE
* and the runtime PM usage counter is nonzero, increment the counter and
* return 1. Otherwise return 0 without changing the counter.
*/
int pm_runtime_get_if_in_use(struct device *dev)
{
unsigned long flags;
int retval;
spin_lock_irqsave(&dev->power.lock, flags);
retval = dev->power.disable_depth > 0 ? -EINVAL :
dev->power.runtime_status == RPM_ACTIVE
&& atomic_inc_not_zero(&dev->power.usage_count);
spin_unlock_irqrestore(&dev->power.lock, flags);
return retval;
}
EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
/**
* __pm_runtime_set_status - Set runtime PM status of a device.
* @dev: Device to handle.