[RFC][PATCH] regulator: Fix _regulator_get_voltage if get_voltage callback is NULL

[Axel Lin <axel.lin@gmail.com>]

In the case of get_voltage callback is NULL, current implementation in
_regulator_get_voltage will return -EINVAL.

Also returns proper error if ret is negative value.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
hi Mark,
I just found in commit 6b8e70 "regulator: Convert WM8400 to get_voltage_sel()",
you added get_voltage_sel callback and remove get_voltage callback.
I suspect you will hit this bug. Can you check it?

Thanks,
Axel

 drivers/regulator/core.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 9493f61..2262474 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1886,13 +1886,15 @@ static int _regulator_get_voltage(struct regulator_dev *rdev)
 		if (sel < 0)
 			return sel;
 		ret = rdev->desc->ops->list_voltage(rdev, sel);
+		goto out;
 	}
 	if (rdev->desc->ops->get_voltage)
 		ret = rdev->desc->ops->get_voltage(rdev);
 	else
 		return -EINVAL;
 
-	return ret - rdev->constraints->uV_offset;
+out:
+	return ret < 0 ? ret : ret - rdev->constraints->uV_offset;
 }
 
 /**
-- 
1.7.1