regulator: Only enable disabled regulators on resume

The _regulator_do_enable() call ought to be a no-op when called on an
already-enabled regulator.  However, as an optimization
_regulator_enable() doesn't call _regulator_do_enable() on an already
enabled regulator.  That means we never test the case of calling
_regulator_do_enable() during normal usage and there may be hidden
bugs or warnings.  We have seen warnings issued by the tps65090 driver
and bugs when using the GPIO enable pin.

Let's match the same optimization that _regulator_enable() in
regulator_suspend_finish().  That may speed up suspend/resume and also
avoids exposing hidden bugs.

[Use much clearer commit message from Doug Anderson]

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index b899947d839d87b03608d1f9bf4b4208cf57aa01..0e271e57504a12092867bcb992b033e18b97a6b6 100644 (file)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -3807,9 +3807,11 @@ int regulator_suspend_finish(void)
        list_for_each_entry(rdev, &regulator_list, list) {
                mutex_lock(&rdev->mutex);
                if (rdev->use_count > 0  || rdev->constraints->always_on) {
-                       error = _regulator_do_enable(rdev);
-                       if (error)
-                               ret = error;
+                       if (!_regulator_is_enabled(rdev)) {
+                               error = _regulator_do_enable(rdev);
+                               if (error)
+                                       ret = error;
+                       }
                } else {
                        if (!have_full_constraints())
                                goto unlock;