Commit 1d9174fb authored by Ulf Hansson's avatar Ulf Hansson Committed by Rafael J. Wysocki
Browse files

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: default avatarUlf Hansson <ulf.hansson@linaro.org>
Tested-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Tested-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: default avatarKevin Hilman <khilman@baylibre.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent a8636c89

drivers/base/power/runtime.c

+30 −5
Original line number Diff line number Diff line
@@ -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;

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