Merge tag 'pm-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management update from Rafael Wysocki:
 "Allow the operating performance points (OPP) core to be used in the
  case when the same driver is used on different platforms, some of
  which have an OPP table and some of which have a clock node (Rajendra
  Nayak)"

* tag 'pm-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  opp: Manage empty OPP tables with clk handle

drivers/opp/core.c

@@ -819,6 +819,8 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 	if (unlikely(!target_freq)) {
 		if (opp_table->required_opp_tables) {
 			ret = _set_required_opps(dev, opp_table, NULL);
+		} else if (!_get_opp_count(opp_table)) {
+			return 0;
 		} else {
 			dev_err(dev, "target frequency can't be 0\n");
 			ret = -EINVAL;
@@ -849,6 +851,18 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
 		goto put_opp_table;
 	}
 
+	/*
+	 * For IO devices which require an OPP on some platforms/SoCs
+	 * while just needing to scale the clock on some others
+	 * we look for empty OPP tables with just a clock handle and
+	 * scale only the clk. This makes dev_pm_opp_set_rate()
+	 * equivalent to a clk_set_rate()
+	 */
+	if (!_get_opp_count(opp_table)) {
+		ret = _generic_set_opp_clk_only(dev, clk, freq);
+		goto put_opp_table;
+	}
+
 	temp_freq = old_freq;
 	old_opp = _find_freq_ceil(opp_table, &temp_freq);
 	if (IS_ERR(old_opp)) {