PM / Domains: Simplify detaching a device from its genpd

There's no need to validate the PM domain by using genpd_lookup_dev() when
removing the device via genpd's genpd_dev_pm_detach() function. That's
because this function can't be called, unless there is a valid PM domain
for the device.

To simplify the behaviour, let's move code from pm_genpd_remove_device()
into a new internal function, genpd_remove_device(), which is called from
pm_genpd_remove_device() and genpd_dev_pm_detach().
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/domain.c

@@ -1121,13 +1121,8 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 }
 EXPORT_SYMBOL_GPL(__pm_genpd_add_device);
 
-/**
- * pm_genpd_remove_device - Remove a device from an I/O PM domain.
- * @genpd: PM domain to remove the device from.
- * @dev: Device to be removed.
- */
-int pm_genpd_remove_device(struct generic_pm_domain *genpd,
-			   struct device *dev)
+static int genpd_remove_device(struct generic_pm_domain *genpd,
+			       struct device *dev)
 {
 	struct generic_pm_domain_data *gpd_data;
 	struct pm_domain_data *pdd;
@@ -1135,10 +1130,6 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 
 	dev_dbg(dev, "%s()\n", __func__);
 
-	if (!genpd || genpd != genpd_lookup_dev(dev))
-		return -EINVAL;
-
-	/* The above validation also means we have existing domain_data. */
 	pdd = dev->power.subsys_data->domain_data;
 	gpd_data = to_gpd_data(pdd);
 	dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
@@ -1170,6 +1161,20 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 
 	return ret;
 }
+
+/**
+ * pm_genpd_remove_device - Remove a device from an I/O PM domain.
+ * @genpd: PM domain to remove the device from.
+ * @dev: Device to be removed.
+ */
+int pm_genpd_remove_device(struct generic_pm_domain *genpd,
+			   struct device *dev)
+{
+	if (!genpd || genpd != genpd_lookup_dev(dev))
+		return -EINVAL;
+
+	return genpd_remove_device(genpd, dev);
+}
 EXPORT_SYMBOL_GPL(pm_genpd_remove_device);
 
 static int genpd_add_subdomain(struct generic_pm_domain *genpd,
@@ -1797,14 +1802,14 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
 	unsigned int i;
 	int ret = 0;
 
-	pd = genpd_lookup_dev(dev);
-	if (!pd)
+	pd = dev_to_genpd(dev);
+	if (IS_ERR(pd))
 		return;
 
 	dev_dbg(dev, "removing from PM domain %s\n", pd->name);
 
 	for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
-		ret = pm_genpd_remove_device(pd, dev);
+		ret = genpd_remove_device(pd, dev);
 		if (ret != -EAGAIN)
 			break;