Merge branch 'pm-domains'

* pm-domains:
  PM / Domains: Fix genpd to deal with drivers returning 1 from ->prepare()
  PM / domains: Rework governor code to be more consistent
  PM / Domains: Remove gpd_dev_ops.active_wakeup() callback
  soc: rockchip: power-domain: Use GENPD_FLAG_ACTIVE_WAKEUP
  soc: mediatek: Use GENPD_FLAG_ACTIVE_WAKEUP
  ARM: shmobile: pm-rmobile: Use GENPD_FLAG_ACTIVE_WAKEUP
  PM / Domains: Allow genpd users to specify default active wakeup behavior
  PM / Domains: Add support to select performance-state of domains
  PM / Domains: Rename genpd internals from pm_genpd_* to genpd_*

2 files changed, 205 insertions, 88 deletions

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index e8ca5e2cf1e5..47fb71a8066a 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -124,6 +124,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
 #define genpd_status_on(genpd)		(genpd->status == GPD_STATE_ACTIVE)
 #define genpd_is_irq_safe(genpd)	(genpd->flags & GENPD_FLAG_IRQ_SAFE)
 #define genpd_is_always_on(genpd)	(genpd->flags & GENPD_FLAG_ALWAYS_ON)
+#define genpd_is_active_wakeup(genpd)	(genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
 
 static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
 		const struct generic_pm_domain *genpd)
@@ -237,6 +238,95 @@ static void genpd_update_accounting(struct generic_pm_domain *genpd)
 static inline void genpd_update_accounting(struct generic_pm_domain *genpd) {}
 #endif
 
+/**
+ * dev_pm_genpd_set_performance_state- Set performance state of device's power
+ * domain.
+ *
+ * @dev: Device for which the performance-state needs to be set.
+ * @state: Target performance state of the device. This can be set as 0 when the
+ *	   device doesn't have any performance state constraints left (And so
+ *	   the device wouldn't participate anymore to find the target
+ *	   performance state of the genpd).
+ *
+ * It is assumed that the users guarantee that the genpd wouldn't be detached
+ * while this routine is getting called.
+ *
+ * Returns 0 on success and negative error values on failures.
+ */
+int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state)
+{
+	struct generic_pm_domain *genpd;
+	struct generic_pm_domain_data *gpd_data, *pd_data;
+	struct pm_domain_data *pdd;
+	unsigned int prev;
+	int ret = 0;
+
+	genpd = dev_to_genpd(dev);
+	if (IS_ERR(genpd))
+		return -ENODEV;
+
+	if (unlikely(!genpd->set_performance_state))
+		return -EINVAL;
+
+	if (unlikely(!dev->power.subsys_data ||
+		     !dev->power.subsys_data->domain_data)) {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	genpd_lock(genpd);
+
+	gpd_data = to_gpd_data(dev->power.subsys_data->domain_data);
+	prev = gpd_data->performance_state;
+	gpd_data->performance_state = state;
+
+	/* New requested state is same as Max requested state */
+	if (state == genpd->performance_state)
+		goto unlock;
+
+	/* New requested state is higher than Max requested state */
+	if (state > genpd->performance_state)
+		goto update_state;
+
+	/* Traverse all devices within the domain */
+	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
+		pd_data = to_gpd_data(pdd);
+
+		if (pd_data->performance_state > state)
+			state = pd_data->performance_state;
+	}
+
+	if (state == genpd->performance_state)
+		goto unlock;
+
+	/*
+	 * We aren't propagating performance state changes of a subdomain to its
+	 * masters as we don't have hardware that needs it. Over that, the
+	 * performance states of subdomain and its masters may not have
+	 * one-to-one mapping and would require additional information. We can
+	 * get back to this once we have hardware that needs it. For that
+	 * reason, we don't have to consider performance state of the subdomains
+	 * of genpd here.
+	 */
+
+update_state:
+	if (genpd_status_on(genpd)) {
+		ret = genpd->set_performance_state(genpd, state);
+		if (ret) {
+			gpd_data->performance_state = prev;
+			goto unlock;
+		}
+	}
+
+	genpd->performance_state = state;
+
+unlock:
+	genpd_unlock(genpd);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_genpd_set_performance_state);
+
 static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
 {
 	unsigned int state_idx = genpd->state_idx;
@@ -256,6 +346,15 @@ static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
 		return ret;
 
 	elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
+
+	if (unlikely(genpd->set_performance_state)) {
+		ret = genpd->set_performance_state(genpd, genpd->performance_state);
+		if (ret) {
+			pr_warn("%s: Failed to set performance state %d (%d)\n",
+				genpd->name, genpd->performance_state, ret);
+		}
+	}
+
 	if (elapsed_ns <= genpd->states[state_idx].power_on_latency_ns)
 		return ret;
 
@@ -749,11 +848,7 @@ late_initcall(genpd_power_off_unused);
 
 #if defined(CONFIG_PM_SLEEP) || defined(CONFIG_PM_GENERIC_DOMAINS_OF)
 
-/**
- * pm_genpd_present - Check if the given PM domain has been initialized.
- * @genpd: PM domain to check.
- */
-static bool pm_genpd_present(const struct generic_pm_domain *genpd)
+static bool genpd_present(const struct generic_pm_domain *genpd)
 {
 	const struct generic_pm_domain *gpd;
 
@@ -771,12 +866,6 @@ static bool pm_genpd_present(const struct generic_pm_domain *genpd)
 
 #ifdef CONFIG_PM_SLEEP
 
-static bool genpd_dev_active_wakeup(const struct generic_pm_domain *genpd,
-				    struct device *dev)
-{
-	return GENPD_DEV_CALLBACK(genpd, bool, active_wakeup, dev);
-}
-
 /**
  * genpd_sync_power_off - Synchronously power off a PM domain and its masters.
  * @genpd: PM domain to power off, if possible.
@@ -863,7 +952,7 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
  * @genpd: PM domain the device belongs to.
  *
  * There are two cases in which a device that can wake up the system from sleep
- * states should be resumed by pm_genpd_prepare(): (1) if the device is enabled
+ * states should be resumed by genpd_prepare(): (1) if the device is enabled
  * to wake up the system and it has to remain active for this purpose while the
  * system is in the sleep state and (2) if the device is not enabled to wake up
  * the system from sleep states and it generally doesn't generate wakeup signals
@@ -881,12 +970,12 @@ static bool resume_needed(struct device *dev,
 	if (!device_can_wakeup(dev))
 		return false;
 
-	active_wakeup = genpd_dev_active_wakeup(genpd, dev);
+	active_wakeup = genpd_is_active_wakeup(genpd);
 	return device_may_wakeup(dev) ? active_wakeup : !active_wakeup;
 }
 
 /**
- * pm_genpd_prepare - Start power transition of a device in a PM domain.
+ * genpd_prepare - Start power transition of a device in a PM domain.
  * @dev: Device to start the transition of.
  *
  * Start a power transition of a device (during a system-wide power transition)
@@ -894,7 +983,7 @@ static bool resume_needed(struct device *dev,
  * an object of type struct generic_pm_domain representing a PM domain
  * consisting of I/O devices.
  */
-static int pm_genpd_prepare(struct device *dev)
+static int genpd_prepare(struct device *dev)
 {
 	struct generic_pm_domain *genpd;
 	int ret;
@@ -921,7 +1010,7 @@ static int pm_genpd_prepare(struct device *dev)
 	genpd_unlock(genpd);
 
 	ret = pm_generic_prepare(dev);
-	if (ret) {
+	if (ret < 0) {
 		genpd_lock(genpd);
 
 		genpd->prepared_count--;
@@ -929,7 +1018,8 @@ static int pm_genpd_prepare(struct device *dev)
 		genpd_unlock(genpd);
 	}
 
-	return ret;
+	/* Never return 1, as genpd don't cope with the direct_complete path. */
+	return ret >= 0 ? 0 : ret;
 }
 
 /**
@@ -950,7 +1040,7 @@ static int genpd_finish_suspend(struct device *dev, bool poweroff)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	if (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))
+	if (dev->power.wakeup_path && genpd_is_active_wakeup(genpd))
 		return 0;
 
 	if (poweroff)
@@ -975,13 +1065,13 @@ static int genpd_finish_suspend(struct device *dev, bool poweroff)
 }
 
 /**
- * pm_genpd_suspend_noirq - Completion of suspend of device in an I/O PM domain.
+ * genpd_suspend_noirq - Completion of suspend of device in an I/O PM domain.
  * @dev: Device to suspend.
  *
  * Stop the device and remove power from the domain if all devices in it have
  * been stopped.
  */
-static int pm_genpd_suspend_noirq(struct device *dev)
+static int genpd_suspend_noirq(struct device *dev)
 {
 	dev_dbg(dev, "%s()\n", __func__);
 
@@ -989,12 +1079,12 @@ static int pm_genpd_suspend_noirq(struct device *dev)
 }
 
 /**
- * pm_genpd_resume_noirq - Start of resume of device in an I/O PM domain.
+ * genpd_resume_noirq - Start of resume of device in an I/O PM domain.
  * @dev: Device to resume.
  *
  * Restore power to the device's PM domain, if necessary, and start the device.
  */
-static int pm_genpd_resume_noirq(struct device *dev)
+static int genpd_resume_noirq(struct device *dev)
 {
 	struct generic_pm_domain *genpd;
 	int ret = 0;
@@ -1005,7 +1095,7 @@ static int pm_genpd_resume_noirq(struct device *dev)
 	if (IS_ERR(genpd))
 		return -EINVAL;
 
-	if (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))
+	if (dev->power.wakeup_path && genpd_is_active_wakeup(genpd))
 		return 0;
 
 	genpd_lock(genpd);
@@ -1024,7 +1114,7 @@ static int pm_genpd_resume_noirq(struct device *dev)
 }
 
 /**
- * pm_genpd_freeze_noirq - Completion of freezing a device in an I/O PM domain.
+ * genpd_freeze_noirq - Completion of freezing a device in an I/O PM domain.
  * @dev: Device to freeze.
  *
  * Carry out a late freeze of a device under the assumption that its
@@ -1032,7 +1122,7 @@ static int pm_genpd_resume_noirq(struct device *dev)
  * struct generic_pm_domain representing a power domain consisting of I/O
  * devices.
  */
-static int pm_genpd_freeze_noirq(struct device *dev)
+static int genpd_freeze_noirq(struct device *dev)
 {
 	const struct generic_pm_domain *genpd;
 	int ret = 0;
@@ -1054,13 +1144,13 @@ static int pm_genpd_freeze_noirq(struct device *dev)
 }
 
 /**
- * pm_genpd_thaw_noirq - Early thaw of device in an I/O PM domain.
+ * genpd_thaw_noirq - Early thaw of device in an I/O PM domain.
  * @dev: Device to thaw.
  *
  * Start the device, unless power has been removed from the domain already
  * before the system transition.
  */
-static int pm_genpd_thaw_noirq(struct device *dev)
+static int genpd_thaw_noirq(struct device *dev)
 {
 	const struct generic_pm_domain *genpd;
 	int ret = 0;
@@ -1081,14 +1171,14 @@ static int pm_genpd_thaw_noirq(struct device *dev)
 }
 
 /**
- * pm_genpd_poweroff_noirq - Completion of hibernation of device in an
+ * genpd_poweroff_noirq - Completion of hibernation of device in an
  *   I/O PM domain.
  * @dev: Device to poweroff.
  *
  * Stop the device and remove power from the domain if all devices in it have
  * been stopped.
  */
-static int pm_genpd_poweroff_noirq(struct device *dev)
+static int genpd_poweroff_noirq(struct device *dev)
 {
 	dev_dbg(dev, "%s()\n", __func__);
 
@@ -1096,13 +1186,13 @@ static int pm_genpd_poweroff_noirq(struct device *dev)
 }
 
 /**
- * pm_genpd_restore_noirq - Start of restore of device in an I/O PM domain.
+ * genpd_restore_noirq - Start of restore of device in an I/O PM domain.
  * @dev: Device to resume.
  *
  * Make sure the domain will be in the same power state as before the
  * hibernation the system is resuming from and start the device if necessary.
  */
-static int pm_genpd_restore_noirq(struct device *dev)
+static int genpd_restore_noirq(struct device *dev)
 {
 	struct generic_pm_domain *genpd;
 	int ret = 0;
@@ -1139,7 +1229,7 @@ static int pm_genpd_restore_noirq(struct device *dev)
 }
 
 /**
- * pm_genpd_complete - Complete power transition of a device in a power domain.
+ * genpd_complete - Complete power transition of a device in a power domain.
  * @dev: Device to complete the transition of.
  *
  * Complete a power transition of a device (during a system-wide power
@@ -1147,7 +1237,7 @@ static int pm_genpd_restore_noirq(struct device *dev)
  * domain member of an object of type struct generic_pm_domain representing
  * a power domain consisting of I/O devices.
  */
-static void pm_genpd_complete(struct device *dev)
+static void genpd_complete(struct device *dev)
 {
 	struct generic_pm_domain *genpd;
 
@@ -1180,7 +1270,7 @@ static void genpd_syscore_switch(struct device *dev, bool suspend)
 	struct generic_pm_domain *genpd;
 
 	genpd = dev_to_genpd(dev);
-	if (!pm_genpd_present(genpd))
+	if (!genpd_present(genpd))
 		return;
 
 	if (suspend) {
@@ -1206,14 +1296,14 @@ EXPORT_SYMBOL_GPL(pm_genpd_syscore_poweron);
 
 #else /* !CONFIG_PM_SLEEP */
 
-#define pm_genpd_prepare		NULL
-#define pm_genpd_suspend_noirq		NULL
-#define pm_genpd_resume_noirq		NULL
-#define pm_genpd_freeze_noirq		NULL
-#define pm_genpd_thaw_noirq		NULL
-#define pm_genpd_poweroff_noirq		NULL
-#define pm_genpd_restore_noirq		NULL
-#define pm_genpd_complete		NULL
+#define genpd_prepare		NULL
+#define genpd_suspend_noirq	NULL
+#define genpd_resume_noirq	NULL
+#define genpd_freeze_noirq	NULL
+#define genpd_thaw_noirq	NULL
+#define genpd_poweroff_noirq	NULL
+#define genpd_restore_noirq	NULL
+#define genpd_complete		NULL
 
 #endif /* CONFIG_PM_SLEEP */
 
@@ -1239,7 +1329,7 @@ static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
 
 	gpd_data->base.dev = dev;
 	gpd_data->td.constraint_changed = true;
-	gpd_data->td.effective_constraint_ns = -1;
+	gpd_data->td.effective_constraint_ns = 0;
 	gpd_data->nb.notifier_call = genpd_dev_pm_qos_notifier;
 
 	spin_lock_irq(&dev->power.lock);
@@ -1574,14 +1664,14 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 	genpd->accounting_time = ktime_get();
 	genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
 	genpd->domain.ops.runtime_resume = genpd_runtime_resume;
-	genpd->domain.ops.prepare = pm_genpd_prepare;
-	genpd->domain.ops.suspend_noirq = pm_genpd_suspend_noirq;
-	genpd->domain.ops.resume_noirq = pm_genpd_resume_noirq;
-	genpd->domain.ops.freeze_noirq = pm_genpd_freeze_noirq;
-	genpd->domain.ops.thaw_noirq = pm_genpd_thaw_noirq;
-	genpd->domain.ops.poweroff_noirq = pm_genpd_poweroff_noirq;
-	genpd->domain.ops.restore_noirq = pm_genpd_restore_noirq;
-	genpd->domain.ops.complete = pm_genpd_complete;
+	genpd->domain.ops.prepare = genpd_prepare;
+	genpd->domain.ops.suspend_noirq = genpd_suspend_noirq;
+	genpd->domain.ops.resume_noirq = genpd_resume_noirq;
+	genpd->domain.ops.freeze_noirq = genpd_freeze_noirq;
+	genpd->domain.ops.thaw_noirq = genpd_thaw_noirq;
+	genpd->domain.ops.poweroff_noirq = genpd_poweroff_noirq;
+	genpd->domain.ops.restore_noirq = genpd_restore_noirq;
+	genpd->domain.ops.complete = genpd_complete;
 
 	if (genpd->flags & GENPD_FLAG_PM_CLK) {
 		genpd->dev_ops.stop = pm_clk_suspend;
@@ -1795,7 +1885,7 @@ int of_genpd_add_provider_simple(struct device_node *np,
 
 	mutex_lock(&gpd_list_lock);
 
-	if (pm_genpd_present(genpd)) {
+	if (genpd_present(genpd)) {
 		ret = genpd_add_provider(np, genpd_xlate_simple, genpd);
 		if (!ret) {
 			genpd->provider = &np->fwnode;
@@ -1831,7 +1921,7 @@ int of_genpd_add_provider_onecell(struct device_node *np,
 	for (i = 0; i < data->num_domains; i++) {
 		if (!data->domains[i])
 			continue;
-		if (!pm_genpd_present(data->domains[i]))
+		if (!genpd_present(data->domains[i]))
 			goto error;
 
 		data->domains[i]->provider = &np->fwnode;
@@ -2274,7 +2364,7 @@ EXPORT_SYMBOL_GPL(of_genpd_parse_idle_states);
 #include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/kobject.h>
-static struct dentry *pm_genpd_debugfs_dir;
+static struct dentry *genpd_debugfs_dir;
 
 /*
  * TODO: This function is a slightly modified version of rtpm_status_show
@@ -2302,8 +2392,8 @@ static void rtpm_status_str(struct seq_file *s, struct device *dev)
 	seq_puts(s, p);
 }
 
-static int pm_genpd_summary_one(struct seq_file *s,
-				struct generic_pm_domain *genpd)
+static int genpd_summary_one(struct seq_file *s,
+			struct generic_pm_domain *genpd)
 {
 	static const char * const status_lookup[] = {
 		[GPD_STATE_ACTIVE] = "on",
@@ -2373,7 +2463,7 @@ static int genpd_summary_show(struct seq_file *s, void *data)
 		return -ERESTARTSYS;
 
 	list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
-		ret = pm_genpd_summary_one(s, genpd);
+		ret = genpd_summary_one(s, genpd);
 		if (ret)
 			break;
 	}
@@ -2559,23 +2649,23 @@ define_genpd_debugfs_fops(active_time);
 define_genpd_debugfs_fops(total_idle_time);
 define_genpd_debugfs_fops(devices);
 
-static int __init pm_genpd_debug_init(void)
+static int __init genpd_debug_init(void)
 {
 	struct dentry *d;
 	struct generic_pm_domain *genpd;
 
-	pm_genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
+	genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);
 
-	if (!pm_genpd_debugfs_dir)
+	if (!genpd_debugfs_dir)
 		return -ENOMEM;
 
 	d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
-			pm_genpd_debugfs_dir, NULL, &genpd_summary_fops);
+			genpd_debugfs_dir, NULL, &genpd_summary_fops);
 	if (!d)
 		return -ENOMEM;
 
 	list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
-		d = debugfs_create_dir(genpd->name, pm_genpd_debugfs_dir);
+		d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);
 		if (!d)
 			return -ENOMEM;
 
@@ -2595,11 +2685,11 @@ static int __init pm_genpd_debug_init(void)
 
 	return 0;
 }
-late_initcall(pm_genpd_debug_init);
+late_initcall(genpd_debug_init);
 
-static void __exit pm_genpd_debug_exit(void)
+static void __exit genpd_debug_exit(void)
 {
-	debugfs_remove_recursive(pm_genpd_debugfs_dir);
+	debugfs_remove_recursive(genpd_debugfs_dir);
 }
-__exitcall(pm_genpd_debug_exit);
+__exitcall(genpd_debug_exit);
 #endif /* CONFIG_DEBUG_FS */
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
index 281f949c5ffe..e4cca8adab32 100644
--- a/drivers/base/power/domain_governor.c
+++ b/drivers/base/power/domain_governor.c
@@ -14,22 +14,33 @@
 static int dev_update_qos_constraint(struct device *dev, void *data)
 {
 	s64 *constraint_ns_p = data;
-	s32 constraint_ns = -1;
+	s64 constraint_ns;
 
-	if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
+	if (dev->power.subsys_data && dev->power.subsys_data->domain_data) {
+		/*
+		 * Only take suspend-time QoS constraints of devices into
+		 * account, because constraints updated after the device has
+		 * been suspended are not guaranteed to be taken into account
+		 * anyway.  In order for them to take effect, the device has to
+		 * be resumed and suspended again.
+		 */
 		constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
-
-	if (constraint_ns < 0) {
+	} else {
+		/*
+		 * The child is not in a domain and there's no info on its
+		 * suspend/resume latencies, so assume them to be negligible and
+		 * take its current PM QoS constraint (that's the only thing
+		 * known at this point anyway).
+		 */
 		constraint_ns = dev_pm_qos_read_value(dev);
-		constraint_ns *= NSEC_PER_USEC;
+		if (constraint_ns > 0)
+			constraint_ns *= NSEC_PER_USEC;
 	}
+
+	/* 0 means "no constraint" */
 	if (constraint_ns == 0)
 		return 0;
 
-	/*
-	 * constraint_ns cannot be negative here, because the device has been
-	 * suspended.
-	 */
 	if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
 		*constraint_ns_p = constraint_ns;
 
@@ -76,14 +87,32 @@ static bool default_suspend_ok(struct device *dev)
 		device_for_each_child(dev, &constraint_ns,
 				      dev_update_qos_constraint);
 
-	if (constraint_ns > 0) {
+	if (constraint_ns == 0) {
+		/* "No restriction", so the device is allowed to suspend. */
+		td->effective_constraint_ns = 0;
+		td->cached_suspend_ok = true;
+	} else if (constraint_ns < 0) {
+		/*
+		 * This triggers if one of the children that don't belong to a
+		 * domain has a negative PM QoS constraint and it's better not
+		 * to suspend then.  effective_constraint_ns is negative already
+		 * and cached_suspend_ok is false, so bail out.
+		 */
+		return false;
+	} else {
 		constraint_ns -= td->suspend_latency_ns +
 				td->resume_latency_ns;
-		if (constraint_ns == 0)
+		/*
+		 * effective_constraint_ns is negative already and
+		 * cached_suspend_ok is false, so if the computed value is not
+		 * positive, return right away.
+		 */
+		if (constraint_ns <= 0)
 			return false;
+
+		td->effective_constraint_ns = constraint_ns;
+		td->cached_suspend_ok = true;
 	}
-	td->effective_constraint_ns = constraint_ns;
-	td->cached_suspend_ok = constraint_ns >= 0;
 
 	/*
 	 * The children have been suspended already, so we don't need to take
@@ -144,18 +173,16 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd,
 		 */
 		td = &to_gpd_data(pdd)->td;
 		constraint_ns = td->effective_constraint_ns;
-		/* default_suspend_ok() need not be called before us. */
-		if (constraint_ns < 0) {
-			constraint_ns = dev_pm_qos_read_value(pdd->dev);
-			constraint_ns *= NSEC_PER_USEC;
-		}
+		/*
+		 * Negative values mean "no suspend at all" and this runs only
+		 * when all devices in the domain are suspended, so it must be
+		 * 0 at least.
+		 *
+		 * 0 means "no constraint"
+		 */
 		if (constraint_ns == 0)
 			continue;
 
-		/*
-		 * constraint_ns cannot be negative here, because the device has
-		 * been suspended.
-		 */
 		if (constraint_ns <= off_on_time_ns)
 			return false;