regulator: enable supply regulator only when use count is zero

Supply regulators are disabled only when the last
reference count is removed on the child regulator
(the use count goes from 1 to 0). This patch changes
the behaviour of enable so the supply regulator is
enabled only when the use count of the child
regulator goes from 0 to 1.
Signed-off-by: Bengt Jonsson <bengt.g.jonsson@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/core.c

@@ -1273,15 +1273,17 @@ static int _regulator_enable(struct regulator_dev *rdev)
 {
 	int ret, delay;
 
-	/* do we need to enable the supply regulator first */
-	if (rdev->supply) {
-		mutex_lock(&rdev->supply->mutex);
-		ret = _regulator_enable(rdev->supply);
-		mutex_unlock(&rdev->supply->mutex);
-		if (ret < 0) {
-			printk(KERN_ERR "%s: failed to enable %s: %d\n",
-			       __func__, rdev_get_name(rdev), ret);
-			return ret;
+	if (rdev->use_count == 0) {
+		/* do we need to enable the supply regulator first */
+		if (rdev->supply) {
+			mutex_lock(&rdev->supply->mutex);
+			ret = _regulator_enable(rdev->supply);
+			mutex_unlock(&rdev->supply->mutex);
+			if (ret < 0) {
+				printk(KERN_ERR "%s: failed to enable %s: %d\n",
+				       __func__, rdev_get_name(rdev), ret);
+				return ret;
+			}
 		}
 	}