Commit 80de3d7f authored Jun 16, 2012 by Rafael J. Wysocki

PM / Domains: Do not stop devices after restoring their states



While resuming a device belonging to a PM domain,
pm_genpd_runtime_resume() calls __pm_genpd_restore_device() to
restore its state, if necessary.  The latter starts the device,
using genpd_start_dev(), restores its state, using
genpd_restore_dev(), and then stops it, using genpd_stop_dev().
However, this last operation is not necessary, because the
device is supposed to be operational after pm_genpd_runtime_resume()
has returned and because of it pm_genpd_runtime_resume() has to
call genpd_start_dev() once again for the "restored" device, which
is inefficient.

To make things more efficient, remove the call to genpd_stop_dev()
from __pm_genpd_restore_device() and the direct call to
genpd_start_dev() from pm_genpd_runtime_resume().  [Of course,
genpd_start_dev() still has to be called by it for devices with the
power.irq_safe flag set, because __pm_genpd_restore_device() is not
executed for them.]

This change has been tested on the SH7372 Mackerel board.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

parent 0b589741

drivers/base/power/domain.c

+5 −11

Original line number	Diff line number	Diff line
		@@ -339,19 +339,16 @@ static void __pm_genpd_restore_device(struct pm_domain_data *pdd,
		{
		struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);
		struct device *dev = pdd->dev;
		bool need_restore = gpd_data->need_restore;

		if (!gpd_data->need_restore)
		return;

		gpd_data->need_restore = false;
		mutex_unlock(&genpd->lock);

		genpd_start_dev(genpd, dev);
		if (need_restore)
		genpd_restore_dev(genpd, dev);
		genpd_stop_dev(genpd, dev);

		mutex_lock(&genpd->lock);

		gpd_data->need_restore = false;
		}

		/**
		@@ -595,7 +592,7 @@ static int pm_genpd_runtime_resume(struct device *dev)

		/* If power.irq_safe, the PM domain is never powered off. */
		if (dev->power.irq_safe)
		goto out;
		return genpd_start_dev(genpd, dev);

		mutex_lock(&genpd->lock);
		ret = __pm_genpd_poweron(genpd);
		@@ -628,9 +625,6 @@ static int pm_genpd_runtime_resume(struct device *dev)
		wake_up_all(&genpd->status_wait_queue);
		mutex_unlock(&genpd->lock);

		out:
		genpd_start_dev(genpd, dev);

		return 0;
		}

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