[PATCH v1] regulator: defer probe when trying to get voltage from unresolved supply

["Michał Mirosław" <mirq-linux@rere.qmqm.pl>]

regulator_get_voltage_rdev() is called in regulator probe() when
applying machine constraints.  The "fixed" commit exposed the problem
that non-bypassed regulators can forward the request to its parent
(like bypassed ones) supply. Return -EPROBE_DEFER when the supply
is expected but not resolved yet.

Fixes: aea6cb99703e ("regulator: resolve supply after creating regulator")
Cc: stable@vger.kernel.org
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reported-by: Ondřej Jirman <megous@megous.com>
Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
---
 v1: this is a bit different solution than the hack sent earlier. It should
     be equivalent (putting the error code at the source), but please
     test again.
---
 drivers/regulator/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index a4ffd71696da..a5ad553da8cd 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -4165,6 +4165,8 @@ int regulator_get_voltage_rdev(struct regulator_dev *rdev)
 		ret = rdev->desc->fixed_uV;
 	} else if (rdev->supply) {
 		ret = regulator_get_voltage_rdev(rdev->supply->rdev);
+	} else if (rdev->supply_name) {
+		return -EPROBE_DEFER;
 	} else {
 		return -EINVAL;
 	}
-- 
2.20.1


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