PM / Domains: Preliminary support for devices with power.irq_safe set

The generic PM domains framework currently doesn't work with devices
whose power.irq_safe flag is set, because runtime PM callbacks for
such devices are run with interrupts disabled and the callbacks
provided by the generic PM domains framework use domain mutexes
and may sleep.  However, such devices very well may belong to
power domains on some systems, so the generic PM domains framework
should take them into account.

For this reason, modify the generic PM domains framework so that the
domain .power_off() and .power_on() callbacks are never executed for
a domain containing devices with power.irq_safe set, although the
.stop_device() and .start_device() callbacks are still run for them.

Additionally, introduce a flag allowing the creator of a
struct generic_pm_domain object to indicate that its .stop_device()
and .start_device() callbacks may be run in interrupt context
(might_sleep_if() triggers if that flag is not set and one of those
callbacks is run in interrupt context).

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

diff --git a/arch/arm/mach-shmobile/pm-sh7372.c b/arch/arm/mach-shmobile/pm-sh7372.c
index 5d35831e4fb1a8ba70a9b86a3e31b68b8d2d89b5..ac47bfcd287eee6f8a7f22e54927a453d1c7e161 100644 (file)
--- a/arch/arm/mach-shmobile/pm-sh7372.c
+++ b/arch/arm/mach-shmobile/pm-sh7372.c
@@ -103,6 +103,7 @@ void sh7372_init_pm_domain(struct sh7372_pm_domain *sh7372_pd)
        pm_genpd_init(genpd, NULL, false);
        genpd->stop_device = pm_clk_suspend;
        genpd->start_device = pm_clk_resume;
+       genpd->dev_irq_safe = true;
        genpd->active_wakeup = pd_active_wakeup;
        genpd->power_off = pd_power_down;
        genpd->power_on = pd_power_up;

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 339eb2d9bddab16678048c9526672b4bb4e2139b..c2468a7e5b219e226100a4a1aea75553a23794e3 100644 (file)
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -309,7 +309,8 @@ static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
 
        not_suspended = 0;
        list_for_each_entry(pdd, &genpd->dev_list, list_node)
-               if (pdd->dev->driver && !pm_runtime_suspended(pdd->dev))
+               if (pdd->dev->driver && (!pm_runtime_suspended(pdd->dev)
+                   || pdd->dev->power.irq_safe))
                        not_suspended++;
 
        if (not_suspended > genpd->in_progress)
@@ -417,12 +418,21 @@ static int pm_genpd_runtime_suspend(struct device *dev)
        if (IS_ERR(genpd))
                return -EINVAL;
 
+       might_sleep_if(!genpd->dev_irq_safe);
+
        if (genpd->stop_device) {
                int ret = genpd->stop_device(dev);
                if (ret)
                        return ret;
        }
 
+       /*
+        * If power.irq_safe is set, this routine will be run with interrupts
+        * off, so it can't use mutexes.
+        */
+       if (dev->power.irq_safe)
+               return 0;
+
        mutex_lock(&genpd->lock);
        genpd->in_progress++;
        pm_genpd_poweroff(genpd);
@@ -452,6 +462,12 @@ static int pm_genpd_runtime_resume(struct device *dev)
        if (IS_ERR(genpd))
                return -EINVAL;
 
+       might_sleep_if(!genpd->dev_irq_safe);
+
+       /* If power.irq_safe, the PM domain is never powered off. */
+       if (dev->power.irq_safe)
+               goto out;
+
        mutex_lock(&genpd->lock);
        ret = __pm_genpd_poweron(genpd);
        if (ret) {
@@ -483,6 +499,7 @@ static int pm_genpd_runtime_resume(struct device *dev)
        wake_up_all(&genpd->status_wait_queue);
        mutex_unlock(&genpd->lock);
 
+ out:
        if (genpd->start_device)
                genpd->start_device(dev);
 

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 5cce46c2d926a062a56585d683b6f9c266ad7c14..2538d906bcd1d94e941590e603e32e729661d7b2 100644 (file)
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -42,6 +42,7 @@ struct generic_pm_domain {
        unsigned int suspended_count;   /* System suspend device counter */
        unsigned int prepared_count;    /* Suspend counter of prepared devices */
        bool suspend_power_off; /* Power status before system suspend */
+       bool dev_irq_safe;      /* Device callbacks are IRQ-safe */
        int (*power_off)(struct generic_pm_domain *domain);
        int (*power_on)(struct generic_pm_domain *domain);
        int (*start_device)(struct device *dev);