MALI: bifrost: Avoid GPU voltage domain keeping the initial voltage

If there is only one opp whose frequency is equal to the initial value
in opp table list, the GPU voltage domain will keep the initial voltage,
it may be too large.

Change-Id: If2ae1c876de185d810e05296b1b9e98855c3ef48
Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>

Author: finley1226

drivers/gpu/arm/bifrost/backend/gpu/mali_kbase_devfreq.c

@@ -103,6 +103,16 @@ kbase_devfreq_target(struct device *dev, unsigned long *target_freq, u32 flags)
 	 */
 	if (kbdev->current_nominal_freq == nominal_freq) {
 		*target_freq = nominal_freq;
+#ifdef CONFIG_REGULATOR
+		if (kbdev->current_voltage == voltage)
+			return 0;
+		err = regulator_set_voltage(kbdev->regulator, voltage, voltage);
+		if (err) {
+			dev_err(dev, "Failed to set voltage (%d)\n", err);
+			return err;
+		}
+		kbdev->current_voltage = voltage;
+#endif
 		return 0;
 	}
 
@@ -318,6 +328,11 @@ int kbase_devfreq_init(struct kbase_device *kbdev)
 
 	kbdev->current_freq = clk_get_rate(kbdev->clock);
 	kbdev->current_nominal_freq = kbdev->current_freq;
+#ifdef CONFIG_REGULATOR
+	if (kbdev->regulator)
+		kbdev->current_voltage =
+			regulator_get_voltage(kbdev->regulator);
+#endif
 
 	dp = &kbdev->devfreq_profile;