[PATCH 5.9 067/133] regulator: defer probe when trying to get voltage from unresolved supply

[Greg Kroah-Hartman]

From: Michał Mirosław <mirq-li...@rere.qmqm.pl>

commit cf1ad559a20d1930aa7b47a52f54e1f8718de301 upstream.

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: sta...@vger.kernel.org
Signed-off-by: Michał Mirosław <mirq-li...@rere.qmqm.pl>
Reported-by: Ondřej Jirman <meg...@megous.com>
Reported-by: Corentin Labbe <clabbe.montj...@gmail.com>
Tested-by: Ondřej Jirman <meg...@megous.com>
Link: 
https://lore.kernel.org/r/a9041d68b4d35e4a2dd71629c8a6422662acb5ee.1604351936.git.mirq-li...@rere.qmqm.pl
Signed-off-by: Mark Brown <broo...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/regulator/core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -4128,6 +4128,8 @@ int regulator_get_voltage_rdev(struct re
                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;
        }