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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <mirq-linux@rere.qmqm.pl>,
        =?UTF-8?q?Ond=C5=99ej=20Jirman?= <megous@megous.com>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH 5.9 067/133] regulator: defer probe when trying to get voltage from unresolved supply
Date:   Mon,  9 Nov 2020 13:55:29 +0100
Message-Id: <20201109125033.957823889@linuxfoundation.org>
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From: Michał Mirosław <mirq-linux@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: 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>
Tested-by: Ondřej Jirman <megous@megous.com>
Link: https://lore.kernel.org/r/a9041d68b4d35e4a2dd71629c8a6422662acb5ee.1604351936.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@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;
 	}