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PM / Runtime: Defer resuming of the device in pm_runtime_force_resume() 

When the pm_runtime_force_suspend|resume() helpers were invented, we still
had CONFIG_PM_RUNTIME and CONFIG_PM_SLEEP as separate Kconfig options.

To make sure these helpers worked for all combinations and without
introducing too much of complexity, the device was always resumed in
pm_runtime_force_resume().

More precisely, when CONFIG_PM_SLEEP was set and CONFIG_PM_RUNTIME was
unset, we needed to resume the device as the subsystem/driver couldn't
rely on using runtime PM to do it.

As the CONFIG_PM_RUNTIME option was merged into CONFIG_PM a while ago, it
removed this combination, of using CONFIG_PM_SLEEP without the earlier
CONFIG_PM_RUNTIME.

For this reason we can now rely on the subsystem/driver to use runtime PM
to resume the device, instead of forcing that to be done in all cases. In
other words, let's defer the runtime resume to a later point when it's
actually needed.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
zero-colors
Ulf Hansson 2016-10-13 16:58:54 +02:00 committed by Rafael J. Wysocki
parent a8636c8964
commit 1d9174fbc5
1 changed files with 30 additions and 5 deletions
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35
drivers/base/power/runtime.c
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@ -1489,6 +1489,16 @@ int pm_runtime_force_suspend(struct device *dev)
if (ret)
goto err;
/*
* Increase the runtime PM usage count for the device's parent, in case
* when we find the device being used when system suspend was invoked.
* This informs pm_runtime_force_resume() to resume the parent
* immediately, which is needed to be able to resume its children,
* when not deferring the resume to be managed via runtime PM.
*/
if (dev->parent && atomic_read(&dev->power.usage_count) > 1)
pm_runtime_get_noresume(dev->parent);
pm_runtime_set_suspended(dev);
return 0;
err:
@ -1498,16 +1508,20 @@ err:
EXPORT_SYMBOL_GPL(pm_runtime_force_suspend);
/**
* pm_runtime_force_resume - Force a device into resume state.
* pm_runtime_force_resume - Force a device into resume state if needed.
* @dev: Device to resume.
*
* Prior invoking this function we expect the user to have brought the device
* into low power state by a call to pm_runtime_force_suspend(). Here we reverse
* those actions and brings the device into full power. We update the runtime PM
* status and re-enables runtime PM.
* those actions and brings the device into full power, if it is expected to be
* used on system resume. To distinguish that, we check whether the runtime PM
* usage count is greater than 1 (the PM core increases the usage count in the
* system PM prepare phase), as that indicates a real user (such as a subsystem,
* driver, userspace, etc.) is using it. If that is the case, the device is
* expected to be used on system resume as well, so then we resume it. In the
* other case, we defer the resume to be managed via runtime PM.
*
* Typically this function may be invoked from a system resume callback to make
* sure the device is put into full power state.
* Typically this function may be invoked from a system resume callback.
*/
int pm_runtime_force_resume(struct device *dev)
{
@ -1524,6 +1538,17 @@ int pm_runtime_force_resume(struct device *dev)
if (!pm_runtime_status_suspended(dev))
goto out;
/*
* Decrease the parent's runtime PM usage count, if we increased it
* during system suspend in pm_runtime_force_suspend().
*/
if (atomic_read(&dev->power.usage_count) > 1) {
if (dev->parent)
pm_runtime_put_noidle(dev->parent);
} else {
goto out;
}
ret = pm_runtime_set_active(dev);
if (ret)
goto out;