PM / Domains: Add default power off governor function (v4)

Add a function deciding whether or not a given PM domain should
be powered off on the basis of the PM QoS constraints of devices
belonging to it and their PM QoS timing data.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 3af9f5a..9189619 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -398,6 +398,17 @@
 	}
 
 	genpd->status = GPD_STATE_POWER_OFF;
+	genpd->power_off_time = ktime_get();
+
+	/* Update PM QoS information for devices in the domain. */
+	list_for_each_entry_reverse(pdd, &genpd->dev_list, list_node) {
+		struct gpd_timing_data *td = &to_gpd_data(pdd)->td;
+
+		pm_runtime_update_max_time_suspended(pdd->dev,
+					td->start_latency_ns +
+					td->restore_state_latency_ns +
+					genpd->power_on_latency_ns);
+	}
 
 	list_for_each_entry(link, &genpd->slave_links, slave_node) {
 		genpd_sd_counter_dec(link->master);
@@ -1487,6 +1498,7 @@
 	genpd->resume_count = 0;
 	genpd->device_count = 0;
 	genpd->suspended_count = 0;
+	genpd->max_off_time_ns = -1;
 	genpd->domain.ops.runtime_suspend = pm_genpd_runtime_suspend;
 	genpd->domain.ops.runtime_resume = pm_genpd_runtime_resume;
 	genpd->domain.ops.runtime_idle = pm_generic_runtime_idle;