linux-kernel - [PATCH] regulator: core: fix false positive in regulator_late

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Message-Id: <20220208084645.8686-1-oliver.barta@aptiv.com>
Date:   Tue,  8 Feb 2022 09:46:45 +0100
From:   Oliver Barta <o.barta89@...il.com>
To:     Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Pi-Hsun Shih <pihsun@...omium.org>,
        Rolf Evers-Fischer <Rolf.Evers.Fischer@...iv.com>,
        Oliver Barta <oliver.barta@...iv.com>
Subject: [PATCH] regulator: core: fix false positive in regulator_late_cleanup()

From: Oliver Barta <oliver.barta@...iv.com>

The check done by regulator_late_cleanup() to detect whether a regulator
is on was inconsistent with the check done by _regulator_is_enabled().
While _regulator_is_enabled() takes the enable GPIO into account,
regulator_late_cleanup() was not doing that.

This resulted in a false positive, e.g. when a GPIO-controlled fixed
regulator was used, which was not enabled at boot time, e.g.

reg_disp_1v2: reg_disp_1v2 {
	compatible = "regulator-fixed";
	regulator-name = "display_1v2";
	regulator-min-microvolt = <1200000>;
	regulator-max-microvolt = <1200000>;
	gpio = <&tlmm 148 0>;
	enable-active-high;
};

Such regulator doesn't have an is_enabled() operation. Nevertheless
it's state can be determined based on the enable GPIO. The check in
regulator_late_cleanup() wrongly assumed that the regulator is on and
tried to disable it.

Signed-off-by: Oliver Barta <oliver.barta@...iv.com>
---
 drivers/regulator/core.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 86aa4141efa9..d2553970a67b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -6014,9 +6014,8 @@ core_initcall(regulator_init);
 static int regulator_late_cleanup(struct device *dev, void *data)
 {
 	struct regulator_dev *rdev = dev_to_rdev(dev);
-	const struct regulator_ops *ops = rdev->desc->ops;
 	struct regulation_constraints *c = rdev->constraints;
-	int enabled, ret;
+	int ret;
 
 	if (c && c->always_on)
 		return 0;
@@ -6029,14 +6028,8 @@ static int regulator_late_cleanup(struct device *dev, void *data)
 	if (rdev->use_count)
 		goto unlock;
 
-	/* If we can't read the status assume it's always on. */
-	if (ops->is_enabled)
-		enabled = ops->is_enabled(rdev);
-	else
-		enabled = 1;
-
-	/* But if reading the status failed, assume that it's off. */
-	if (enabled <= 0)
+	/* If reading the status failed, assume that it's off. */
+	if (_regulator_is_enabled(rdev) <= 0)
 		goto unlock;
 
 	if (have_full_constraints()) {
-- 
2.25.1