1 files changed, 36 insertions, 20 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 60fcd986ff3f..dbf27bf028c4 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1191,16 +1191,21 @@ void regulator_put(struct regulator *regulator)
 }
 EXPORT_SYMBOL_GPL(regulator_put);
 
+static int _regulator_can_change_status(struct regulator_dev *rdev)
+{
+        if (!rdev->constraints)
+                return 0;
+
+        if (rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_STATUS)
+                return 1;
+        else
+                return 0;
+}
+
 /* locks held by regulator_enable() */
 static int _regulator_enable(struct regulator_dev *rdev)
 {
-        int ret = -EINVAL;
-
-        if (!rdev->constraints) {
-                printk(KERN_ERR "%s: %s has no constraints\n",
-                       __func__, rdev->desc->name);
-                return ret;
-        }
+        int ret;
 
         /* do we need to enable the supply regulator first */
         if (rdev->supply) {
@@ -1213,24 +1218,34 @@ static int _regulator_enable(struct regulator_dev *rdev)
         }
 
         /* check voltage and requested load before enabling */
-        if (rdev->desc->ops->enable) {
+        if (rdev->constraints &&
+            (rdev->constraints->valid_ops_mask & REGULATOR_CHANGE_DRMS))
+                drms_uA_update(rdev);
 
-                if (rdev->constraints &&
-                        (rdev->constraints->valid_ops_mask &
-                        REGULATOR_CHANGE_DRMS))
-                        drms_uA_update(rdev);
-
-                ret = rdev->desc->ops->enable(rdev);
-                if (ret < 0) {
-                        printk(KERN_ERR "%s: failed to enable %s: %d\n",
+        if (rdev->use_count == 0) {
+                /* The regulator may on if it's not switchable or left on */
+                ret = _regulator_is_enabled(rdev);
+                if (ret == -EINVAL || ret == 0) {
+                        if (!_regulator_can_change_status(rdev))
+                                return -EPERM;
+
+                        if (rdev->desc->ops->enable) {
+                                ret = rdev->desc->ops->enable(rdev);
+                                if (ret < 0)
+                                        return ret;
+                        } else {
+                                return -EINVAL;
+                        }
+                } else {
+                        printk(KERN_ERR "%s: is_enabled() failed for %s: %d\n",
                                __func__, rdev->desc->name, ret);
                         return ret;
                 }
-                rdev->use_count++;
-                return ret;
         }
 
-        return ret;
+        rdev->use_count++;
+
+        return 0;
 }
 
 /**
@@ -1270,7 +1285,8 @@ static int _regulator_disable(struct regulator_dev *rdev)
         if (rdev->use_count == 1 && !rdev->constraints->always_on) {
 
                 /* we are last user */
-                if (rdev->desc->ops->disable) {
+                if (_regulator_can_change_status(rdev) &&
+                    rdev->desc->ops->disable) {
                         ret = rdev->desc->ops->disable(rdev);
                         if (ret < 0) {
                                 printk(KERN_ERR "%s: failed to disable %s\n",