opp: Power on (virtual) power domains managed by the OPP core0/opp/genpd/links

dev_pm_opp_attach_genpd() allows attaching an arbitrary number of
power domains to an OPP table. In that case, the genpd core will
create a virtual device for each of the power domains.

At the moment, the OPP core only calls
dev_pm_genpd_set_performance_state() on these virtual devices.
It does not attempt to power on the power domains. Therefore
the required power domain might never get turned on.

So far, dev_pm_opp_attach_genpd() is only used in qcom-cpufreq-nvmem.c
to attach the CPR power domain to the CPU OPP table. The CPR driver
does not check if it was actually powered on so this did not cause
any problems. However, other drivers (e.g. rpmpd) might ignore the
performance state until the power domain is actually powered on.

Since these virtual devices are managed exclusively by the OPP core,
I would say that it should also be responsible to ensure they are
enabled.

This commit implements this similar to the non-virtual power domains;
we create device links for each of attached power domains so that they
are turned on whenever the consumer device is active.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
[ Viresh: Rearranged the code to remove extra loop and minor cleanup ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

2 files changed, 37 insertions, 1 deletions

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index e65174725a4d..b608b0253079 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -17,6 +17,7 @@
 #include <linux/device.h>
 #include <linux/export.h>
 #include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 
 #include "opp.h"
@@ -1967,10 +1968,15 @@ static void _opp_detach_genpd(struct opp_table *opp_table)
 		if (!opp_table->genpd_virt_devs[index])
 			continue;
 
+		if (opp_table->genpd_virt_links[index])
+			device_link_del(opp_table->genpd_virt_links[index]);
+
 		dev_pm_domain_detach(opp_table->genpd_virt_devs[index], false);
 		opp_table->genpd_virt_devs[index] = NULL;
 	}
 
+	kfree(opp_table->genpd_virt_links);
+	opp_table->genpd_virt_links = NULL;
 	kfree(opp_table->genpd_virt_devs);
 	opp_table->genpd_virt_devs = NULL;
 }
@@ -2002,8 +2008,10 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
 {
 	struct opp_table *opp_table;
 	struct device *virt_dev;
+	struct device_link *dev_link;
 	int index = 0, ret = -EINVAL;
 	const char **name = names;
+	u32 flags;
 
 	opp_table = dev_pm_opp_get_opp_table(dev);
 	if (IS_ERR(opp_table))
@@ -2030,6 +2038,21 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
 	if (!opp_table->genpd_virt_devs)
 		goto unlock;
 
+	opp_table->genpd_virt_links = kcalloc(opp_table->required_opp_count,
+					      sizeof(*opp_table->genpd_virt_links),
+					      GFP_KERNEL);
+	if (!opp_table->genpd_virt_links) {
+		kfree(opp_table->genpd_virt_devs);
+		opp_table->genpd_virt_devs = NULL;
+		goto unlock;
+	}
+
+	/* Turn on power domain initially if consumer is active */
+	pm_runtime_get_noresume(dev);
+	flags = DL_FLAG_PM_RUNTIME | DL_FLAG_STATELESS;
+	if (pm_runtime_active(dev))
+		flags |= DL_FLAG_RPM_ACTIVE;
+
 	while (*name) {
 		if (index >= opp_table->required_opp_count) {
 			dev_err(dev, "Index can't be greater than required-opp-count - 1, %s (%d : %d)\n",
@@ -2043,12 +2066,23 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
 			dev_err(dev, "Couldn't attach to pm_domain: %d\n", ret);
 			goto err;
 		}
-
 		opp_table->genpd_virt_devs[index] = virt_dev;
+
+		/* Create device links to manage runtime PM */
+		dev_link = device_link_add(dev, opp_table->genpd_virt_devs[index],
+					   flags);
+		if (!dev_link) {
+			dev_err(dev, "Failed to create device link\n");
+			goto err;
+		}
+		opp_table->genpd_virt_links[index] = dev_link;
+
 		index++;
 		name++;
 	}
 
+	pm_runtime_put(dev);
+
 	if (virt_devs)
 		*virt_devs = opp_table->genpd_virt_devs;
 	mutex_unlock(&opp_table->genpd_virt_dev_lock);
@@ -2056,6 +2090,7 @@ struct opp_table *dev_pm_opp_attach_genpd(struct device *dev,
 	return opp_table;
 
 err:
+	pm_runtime_put(dev);
 	_opp_detach_genpd(opp_table);
 unlock:
 	mutex_unlock(&opp_table->genpd_virt_dev_lock);
diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index 78e876ec803e..be5526cdbdba 100644
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -186,6 +186,7 @@ struct opp_table {
 
 	struct mutex genpd_virt_dev_lock;
 	struct device **genpd_virt_devs;
+	struct device_link **genpd_virt_links;
 	struct opp_table **required_opp_tables;
 	unsigned int required_opp_count;