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path: root/drivers/base/power/domain_governor.c
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Diffstat (limited to 'drivers/base/power/domain_governor.c')
-rw-r--r--drivers/base/power/domain_governor.c73
1 files changed, 46 insertions, 27 deletions
diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
index 281f949c5ffe..99896fbf18e4 100644
--- a/drivers/base/power/domain_governor.c
+++ b/drivers/base/power/domain_governor.c
@@ -14,23 +14,29 @@
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)
- return 0;
- /*
- * constraint_ns cannot be negative here, because the device has been
- * suspended.
- */
- if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
+ if (constraint_ns < *constraint_ns_p)
*constraint_ns_p = constraint_ns;
return 0;
@@ -58,12 +64,12 @@ static bool default_suspend_ok(struct device *dev)
}
td->constraint_changed = false;
td->cached_suspend_ok = false;
- td->effective_constraint_ns = -1;
+ td->effective_constraint_ns = 0;
constraint_ns = __dev_pm_qos_read_value(dev);
spin_unlock_irqrestore(&dev->power.lock, flags);
- if (constraint_ns < 0)
+ if (constraint_ns == 0)
return false;
constraint_ns *= NSEC_PER_USEC;
@@ -76,14 +82,32 @@ 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 == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS) {
+ /* "No restriction", so the device is allowed to suspend. */
+ td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS;
+ 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 zero PM QoS constraint and it's better not to
+ * suspend then. effective_constraint_ns is zero 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 zero 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 +168,13 @@ 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;
- }
- if (constraint_ns == 0)
- continue;
-
/*
- * constraint_ns cannot be negative here, because the device has
- * been suspended.
+ * Zero means "no suspend at all" and this runs only when all
+ * devices in the domain are suspended, so it must be positive.
*/
+ if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS)
+ continue;
+
if (constraint_ns <= off_on_time_ns)
return false;