opp: Allow required-opps to be used for non genpd use cases

Don't limit required_opp_table to genpd only. One possible use case is
cpufreq based devfreq governor, which can use required-opps property to
derive devfreq from cpufreq.

Though the OPP core still doesn't support non-genpd required-opps in
_set_required_opps().

Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
[ Viresh: Update _set_required_opps() to check for genpd ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: hsinyi527

drivers/opp/core.c

@@ -893,6 +893,16 @@ static int _set_required_opps(struct device *dev,
 	if (!required_opp_tables)
 		return 0;
 
+	/*
+	 * We only support genpd's OPPs in the "required-opps" for now, as we
+	 * don't know much about other use cases. Error out if the required OPP
+	 * doesn't belong to a genpd.
+	 */
+	if (unlikely(!required_opp_tables[0]->is_genpd)) {
+		dev_err(dev, "required-opps don't belong to a genpd\n");
+		return -ENOENT;
+	}
+
 	/* required-opps not fully initialized yet */
 	if (lazy_linking_pending(opp_table))
 		return -EBUSY;

drivers/opp/of.c

@@ -197,21 +197,8 @@ static void _opp_table_alloc_required_tables(struct opp_table *opp_table,
 		required_opp_tables[i] = _find_table_of_opp_np(required_np);
 		of_node_put(required_np);
 
-		if (IS_ERR(required_opp_tables[i])) {
+		if (IS_ERR(required_opp_tables[i]))
 			lazy = true;
-			continue;
-		}
-
-		/*
-		 * We only support genpd's OPPs in the "required-opps" for now,
-		 * as we don't know how much about other cases. Error out if the
-		 * required OPP doesn't belong to a genpd.
-		 */
-		if (!required_opp_tables[i]->is_genpd) {
-			dev_err(dev, "required-opp doesn't belong to genpd: %pOF\n",
-				required_np);
-			goto free_required_tables;
-		}
 	}
 
 	/* Let's do the linking later on */
@@ -379,13 +366,6 @@ static void lazy_link_required_opp_table(struct opp_table *new_table)
 	struct dev_pm_opp *opp;
 	int i, ret;
 
-	/*
-	 * We only support genpd's OPPs in the "required-opps" for now,
-	 * as we don't know much about other cases.
-	 */
-	if (!new_table->is_genpd)
-		return;
-
 	mutex_lock(&opp_table_lock);
 
 	list_for_each_entry_safe(opp_table, temp, &lazy_opp_tables, lazy) {
@@ -873,7 +853,7 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
 		return ERR_PTR(-ENOMEM);
 
 	ret = _read_opp_key(new_opp, opp_table, np, &rate_not_available);
-	if (ret < 0 && !opp_table->is_genpd) {
+	if (ret < 0) {
 		dev_err(dev, "%s: opp key field not found\n", __func__);
 		goto free_opp;
 	}