OPP: Don't set OPP recursively for a parent genpd

Like other frameworks (clk, regulator, etc.) genpd core too takes care
of propagation to performance state to parent genpds. The OPP core
shouldn't attempt the same, or it may result in undefined behavior.

Add checks at various places to take care of the same.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Author: vireshk

drivers/opp/core.c

@@ -2392,6 +2392,12 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
 		return -EINVAL;
 	}
 
+	/* Genpd core takes care of propagation to parent genpd */
+	if (opp_table->is_genpd) {
+		dev_err(dev, "%s: Operation not supported for genpds\n", __func__);
+		return -EOPNOTSUPP;
+	}
+
 	/* Checking only the first one is enough ? */
 	if (opp_table->required_devs[0])
 		return 0;
@@ -2453,8 +2459,16 @@ static int _opp_set_required_devs(struct opp_table *opp_table,
 	if (opp_table->required_devs[0])
 		return 0;
 
-	for (i = 0; i < opp_table->required_opp_count; i++)
+	for (i = 0; i < opp_table->required_opp_count; i++) {
+		/* Genpd core takes care of propagation to parent genpd */
+		if (required_devs[i] && opp_table->is_genpd &&
+		    opp_table->required_opp_tables[i]->is_genpd) {
+			dev_err(dev, "%s: Operation not supported for genpds\n", __func__);
+			return -EOPNOTSUPP;
+		}
+
 		opp_table->required_devs[i] = required_devs[i];
+	}
 
 	return 0;
 }

drivers/opp/of.c

@@ -339,8 +339,11 @@ static int _link_required_opps(struct dev_pm_opp *opp, struct opp_table *opp_tab
 	 */
 	if (required_table->is_genpd && opp_table->required_opp_count == 1 &&
 	    !opp_table->required_devs[0]) {
-		if (!WARN_ON(opp->level != OPP_LEVEL_UNSET))
-			opp->level = opp->required_opps[0]->level;
+		/* Genpd core takes care of propagation to parent genpd */
+		if (!opp_table->is_genpd) {
+			if (!WARN_ON(opp->level != OPP_LEVEL_UNSET))
+				opp->level = opp->required_opps[0]->level;
+		}
 	}
 
 	return 0;