PM / devfreq: tegra: Don't ignore clk errors

The clk_set_min_rate() could fail and in this case clk_set_rate() sets
rate to 0, which may drop EMC rate to minimum and make machine very
difficult to use.
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

drivers/devfreq/tegra-devfreq.c

@@ -472,8 +472,10 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
 				u32 flags)
 {
 	struct tegra_devfreq *tegra = dev_get_drvdata(dev);
+	struct devfreq *devfreq = tegra->devfreq;
 	struct dev_pm_opp *opp;
 	unsigned long rate;
+	int err;
 
 	opp = devfreq_recommended_opp(dev, freq, flags);
 	if (IS_ERR(opp)) {
@@ -483,10 +485,20 @@ static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
 	rate = dev_pm_opp_get_freq(opp);
 	dev_pm_opp_put(opp);
 
-	clk_set_min_rate(tegra->emc_clock, rate);
-	clk_set_rate(tegra->emc_clock, 0);
+	err = clk_set_min_rate(tegra->emc_clock, rate);
+	if (err)
+		return err;
+
+	err = clk_set_rate(tegra->emc_clock, 0);
+	if (err)
+		goto restore_min_rate;
 
 	return 0;
+
+restore_min_rate:
+	clk_set_min_rate(tegra->emc_clock, devfreq->previous_freq);
+
+	return err;
 }
 
 static int tegra_devfreq_get_dev_status(struct device *dev,