PM / QoS: Add no_constraints_value field to struct pm_qos_constraints

Add a new field, no_constraints_value, to struct pm_qos_constraints
representing a list of PM QoS constraint requests to be returned by
pm_qos_get_value() when that list of requests is empty.

That field will be equal to default_value for all of the existing
global PM QoS classes and for the resume latency device PM QoS type,
but it will be different from default_value for the new latency
tolerance device PM QoS type introduced by the next changeset.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/qos.c

@@ -190,6 +190,7 @@ static int dev_pm_qos_constraints_allocate(struct device *dev)
 	plist_head_init(&c->list);
 	c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
 	c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
+	c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;
 	c->type = PM_QOS_MIN;
 	c->notifiers = n;
 

include/linux/pm_qos.h

@@ -77,6 +77,7 @@ struct pm_qos_constraints {
 	struct plist_head list;
 	s32 target_value;	/* Do not change to 64 bit */
 	s32 default_value;
+	s32 no_constraint_value;
 	enum pm_qos_type type;
 	struct blocking_notifier_head *notifiers;
 };

kernel/power/qos.c

@@ -66,6 +66,7 @@ static struct pm_qos_constraints cpu_dma_constraints = {
 	.list = PLIST_HEAD_INIT(cpu_dma_constraints.list),
 	.target_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
 	.default_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
+	.no_constraint_value = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE,
 	.type = PM_QOS_MIN,
 	.notifiers = &cpu_dma_lat_notifier,
 };
@@ -79,6 +80,7 @@ static struct pm_qos_constraints network_lat_constraints = {
 	.list = PLIST_HEAD_INIT(network_lat_constraints.list),
 	.target_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
 	.default_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
+	.no_constraint_value = PM_QOS_NETWORK_LAT_DEFAULT_VALUE,
 	.type = PM_QOS_MIN,
 	.notifiers = &network_lat_notifier,
 };
@@ -93,6 +95,7 @@ static struct pm_qos_constraints network_tput_constraints = {
 	.list = PLIST_HEAD_INIT(network_tput_constraints.list),
 	.target_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
 	.default_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
+	.no_constraint_value = PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE,
 	.type = PM_QOS_MAX,
 	.notifiers = &network_throughput_notifier,
 };
@@ -128,7 +131,7 @@ static const struct file_operations pm_qos_power_fops = {
 static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 {
 	if (plist_head_empty(&c->list))
-		return c->default_value;
+		return c->no_constraint_value;
 
 	switch (c->type) {
 	case PM_QOS_MIN: