PM: domains: Allocate governor data dynamically based on a genpd governor

If a genpd doesn't have an associated governor assigned, several variables
in the struct generic_pm_domain becomes superfluous.

Rather than wasting memory in allocated genpds, let's move the variables
from the struct generic_pm_domain into a new separate struct. In this way,
we can instead dynamically decide when we need to allocate the
corresponding data for it.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -527,7 +527,8 @@ static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
 		goto out;
 
 	genpd->states[state_idx].power_on_latency_ns = elapsed_ns;
-	genpd->max_off_time_changed = true;
+	if (genpd->gd)
+		genpd->gd->max_off_time_changed = true;
 	pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
 		 genpd->name, "on", elapsed_ns);
 
@@ -576,7 +577,8 @@ static int _genpd_power_off(struct generic_pm_domain *genpd, bool timed)
 		goto out;
 
 	genpd->states[state_idx].power_off_latency_ns = elapsed_ns;
-	genpd->max_off_time_changed = true;
+	if (genpd->gd)
+		genpd->gd->max_off_time_changed = true;
 	pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
 		 genpd->name, "off", elapsed_ns);
 
@@ -772,7 +774,7 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
 	dev = gpd_data->base.dev;
 
 	for (;;) {
-		struct generic_pm_domain *genpd;
+		struct generic_pm_domain *genpd = ERR_PTR(-ENODATA);
 		struct pm_domain_data *pdd;
 		struct gpd_timing_data *td;
 
@@ -782,18 +784,17 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
 				dev->power.subsys_data->domain_data : NULL;
 		if (pdd) {
 			td = to_gpd_data(pdd)->td;
-			if (td)
+			if (td) {
 				td->constraint_changed = true;
 				genpd = dev_to_genpd(dev);
-		} else {
-			genpd = ERR_PTR(-ENODATA);
+			}
 		}
 
 		spin_unlock_irq(&dev->power.lock);
 
 		if (!IS_ERR(genpd)) {
 			genpd_lock(genpd);
-			genpd->max_off_time_changed = true;
+			genpd->gd->max_off_time_changed = true;
 			genpd_unlock(genpd);
 		}
 
@@ -922,7 +923,7 @@ static int genpd_runtime_suspend(struct device *dev)
 			td->suspend_latency_ns = elapsed_ns;
 			dev_dbg(dev, "suspend latency exceeded, %lld ns\n",
 				elapsed_ns);
-			genpd->max_off_time_changed = true;
+			genpd->gd->max_off_time_changed = true;
 			td->constraint_changed = true;
 		}
 	}
@@ -1002,7 +1003,7 @@ static int genpd_runtime_resume(struct device *dev)
 			td->resume_latency_ns = elapsed_ns;
 			dev_dbg(dev, "resume latency exceeded, %lld ns\n",
 				elapsed_ns);
-			genpd->max_off_time_changed = true;
+			genpd->gd->max_off_time_changed = true;
 			td->constraint_changed = true;
 		}
 	}
@@ -1617,6 +1618,7 @@ static int genpd_get_cpu(struct generic_pm_domain *genpd, struct device *dev)
 static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 			    struct device *base_dev)
 {
+	struct genpd_governor_data *gd = genpd->gd;
 	struct generic_pm_domain_data *gpd_data;
 	int ret;
 
@@ -1625,7 +1627,7 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
 		return -EINVAL;
 
-	gpd_data = genpd_alloc_dev_data(dev, genpd->gov);
+	gpd_data = genpd_alloc_dev_data(dev, gd);
 	if (IS_ERR(gpd_data))
 		return PTR_ERR(gpd_data);
 
@@ -1641,7 +1643,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	dev_pm_domain_set(dev, &genpd->domain);
 
 	genpd->device_count++;
-	genpd->max_off_time_changed = true;
+	if (gd)
+		gd->max_off_time_changed = true;
 
 	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
 
@@ -1695,7 +1698,8 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
 	}
 
 	genpd->device_count--;
-	genpd->max_off_time_changed = true;
+	if (genpd->gd)
+		genpd->gd->max_off_time_changed = true;
 
 	genpd_clear_cpumask(genpd, gpd_data->cpu);
 	dev_pm_domain_set(dev, NULL);
@@ -1970,12 +1974,25 @@ static int genpd_set_default_power_state(struct generic_pm_domain *genpd)
 
 static int genpd_alloc_data(struct generic_pm_domain *genpd)
 {
+	struct genpd_governor_data *gd = NULL;
 	int ret;
 
 	if (genpd_is_cpu_domain(genpd) &&
 	    !zalloc_cpumask_var(&genpd->cpus, GFP_KERNEL))
 		return -ENOMEM;
 
+	if (genpd->gov) {
+		gd = kzalloc(sizeof(*gd), GFP_KERNEL);
+		if (!gd) {
+			ret = -ENOMEM;
+			goto free;
+		}
+
+		gd->max_off_time_ns = -1;
+		gd->max_off_time_changed = true;
+		gd->next_wakeup = KTIME_MAX;
+	}
+
 	/* Use only one "off" state if there were no states declared */
 	if (genpd->state_count == 0) {
 		ret = genpd_set_default_power_state(genpd);
@@ -1983,11 +2000,13 @@ static int genpd_alloc_data(struct generic_pm_domain *genpd)
 			goto free;
 	}
 
+	genpd->gd = gd;
 	return 0;
 
 free:
 	if (genpd_is_cpu_domain(genpd))
 		free_cpumask_var(genpd->cpus);
+	kfree(gd);
 	return ret;
 }
 
@@ -1997,6 +2016,7 @@ static void genpd_free_data(struct generic_pm_domain *genpd)
 		free_cpumask_var(genpd->cpus);
 	if (genpd->free_states)
 		genpd->free_states(genpd->states, genpd->state_count);
+	kfree(genpd->gd);
 }
 
 static void genpd_lock_init(struct generic_pm_domain *genpd)
@@ -2036,9 +2056,6 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 	atomic_set(&genpd->sd_count, 0);
 	genpd->status = is_off ? GENPD_STATE_OFF : GENPD_STATE_ON;
 	genpd->device_count = 0;
-	genpd->max_off_time_ns = -1;
-	genpd->max_off_time_changed = true;
-	genpd->next_wakeup = KTIME_MAX;
 	genpd->provider = NULL;
 	genpd->has_provider = false;
 	genpd->accounting_time = ktime_get_mono_fast_ns();

drivers/base/power/domain_governor.c

@@ -146,19 +146,21 @@ static void update_domain_next_wakeup(struct generic_pm_domain *genpd, ktime_t n
 	}
 
 	list_for_each_entry(link, &genpd->parent_links, parent_node) {
-		next_wakeup = link->child->next_wakeup;
+		struct genpd_governor_data *cgd = link->child->gd;
+
+		next_wakeup = cgd ? cgd->next_wakeup : KTIME_MAX;
 		if (next_wakeup != KTIME_MAX && !ktime_before(next_wakeup, now))
 			if (ktime_before(next_wakeup, domain_wakeup))
 				domain_wakeup = next_wakeup;
 	}
 
-	genpd->next_wakeup = domain_wakeup;
+	genpd->gd->next_wakeup = domain_wakeup;
 }
 
 static bool next_wakeup_allows_state(struct generic_pm_domain *genpd,
 				     unsigned int state, ktime_t now)
 {
-	ktime_t domain_wakeup = genpd->next_wakeup;
+	ktime_t domain_wakeup = genpd->gd->next_wakeup;
 	s64 idle_time_ns, min_sleep_ns;
 
 	min_sleep_ns = genpd->states[state].power_off_latency_ns +
@@ -188,8 +190,9 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd,
 	 * All subdomains have been powered off already at this point.
 	 */
 	list_for_each_entry(link, &genpd->parent_links, parent_node) {
-		struct generic_pm_domain *sd = link->child;
-		s64 sd_max_off_ns = sd->max_off_time_ns;
+		struct genpd_governor_data *cgd = link->child->gd;
+
+		s64 sd_max_off_ns = cgd ? cgd->max_off_time_ns : -1;
 
 		if (sd_max_off_ns < 0)
 			continue;
@@ -247,7 +250,7 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd,
 	 * time and the time needed to turn the domain on is the maximum
 	 * theoretical time this domain can spend in the "off" state.
 	 */
-	genpd->max_off_time_ns = min_off_time_ns -
+	genpd->gd->max_off_time_ns = min_off_time_ns -
 		genpd->states[state].power_on_latency_ns;
 	return true;
 }
@@ -262,6 +265,7 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd,
 static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now)
 {
 	struct generic_pm_domain *genpd = pd_to_genpd(pd);
+	struct genpd_governor_data *gd = genpd->gd;
 	int state_idx = genpd->state_count - 1;
 	struct gpd_link *link;
 
@@ -272,11 +276,11 @@ static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now)
 	 * cannot be met.
 	 */
 	update_domain_next_wakeup(genpd, now);
-	if ((genpd->flags & GENPD_FLAG_MIN_RESIDENCY) && (genpd->next_wakeup != KTIME_MAX)) {
+	if ((genpd->flags & GENPD_FLAG_MIN_RESIDENCY) && (gd->next_wakeup != KTIME_MAX)) {
 		/* Let's find out the deepest domain idle state, the devices prefer */
 		while (state_idx >= 0) {
 			if (next_wakeup_allows_state(genpd, state_idx, now)) {
-				genpd->max_off_time_changed = true;
+				gd->max_off_time_changed = true;
 				break;
 			}
 			state_idx--;
@@ -284,14 +288,14 @@ static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now)
 
 		if (state_idx < 0) {
 			state_idx = 0;
-			genpd->cached_power_down_ok = false;
+			gd->cached_power_down_ok = false;
 			goto done;
 		}
 	}
 
-	if (!genpd->max_off_time_changed) {
-		genpd->state_idx = genpd->cached_power_down_state_idx;
-		return genpd->cached_power_down_ok;
+	if (!gd->max_off_time_changed) {
+		genpd->state_idx = gd->cached_power_down_state_idx;
+		return gd->cached_power_down_ok;
 	}
 
 	/*
@@ -300,12 +304,16 @@ static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now)
 	 * going to be called for any parent until this instance
 	 * returns.
 	 */
-	list_for_each_entry(link, &genpd->child_links, child_node)
-		link->parent->max_off_time_changed = true;
+	list_for_each_entry(link, &genpd->child_links, child_node) {
+		struct genpd_governor_data *pgd = link->parent->gd;
+
+		if (pgd)
+			pgd->max_off_time_changed = true;
+	}
 
-	genpd->max_off_time_ns = -1;
-	genpd->max_off_time_changed = false;
-	genpd->cached_power_down_ok = true;
+	gd->max_off_time_ns = -1;
+	gd->max_off_time_changed = false;
+	gd->cached_power_down_ok = true;
 
 	/*
 	 * Find a state to power down to, starting from the state
@@ -313,7 +321,7 @@ static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now)
 	 */
 	while (!__default_power_down_ok(pd, state_idx)) {
 		if (state_idx == 0) {
-			genpd->cached_power_down_ok = false;
+			gd->cached_power_down_ok = false;
 			break;
 		}
 		state_idx--;
@@ -321,8 +329,8 @@ static bool _default_power_down_ok(struct dev_pm_domain *pd, ktime_t now)
 
 done:
 	genpd->state_idx = state_idx;
-	genpd->cached_power_down_state_idx = genpd->state_idx;
-	return genpd->cached_power_down_ok;
+	gd->cached_power_down_state_idx = genpd->state_idx;
+	return gd->cached_power_down_ok;
 }
 
 static bool default_power_down_ok(struct dev_pm_domain *pd)

include/linux/pm_domain.h

@@ -91,6 +91,14 @@ struct gpd_dev_ops {
 	int (*stop)(struct device *dev);
 };
 
+struct genpd_governor_data {
+	s64 max_off_time_ns;
+	bool max_off_time_changed;
+	ktime_t next_wakeup;
+	bool cached_power_down_ok;
+	bool cached_power_down_state_idx;
+};
+
 struct genpd_power_state {
 	s64 power_off_latency_ns;
 	s64 power_on_latency_ns;
@@ -114,6 +122,7 @@ struct generic_pm_domain {
 	struct list_head child_links;	/* Links with PM domain as a child */
 	struct list_head dev_list;	/* List of devices */
 	struct dev_power_governor *gov;
+	struct genpd_governor_data *gd;	/* Data used by a genpd governor. */
 	struct work_struct power_off_work;
 	struct fwnode_handle *provider;	/* Identity of the domain provider */
 	bool has_provider;
@@ -134,11 +143,6 @@ struct generic_pm_domain {
 	int (*set_performance_state)(struct generic_pm_domain *genpd,
 				     unsigned int state);
 	struct gpd_dev_ops dev_ops;
-	s64 max_off_time_ns;	/* Maximum allowed "suspended" time. */
-	ktime_t next_wakeup;	/* Maintained by the domain governor */
-	bool max_off_time_changed;
-	bool cached_power_down_ok;
-	bool cached_power_down_state_idx;
 	int (*attach_dev)(struct generic_pm_domain *domain,
 			  struct device *dev);
 	void (*detach_dev)(struct generic_pm_domain *domain,