From: Oliver Barta <oliver.barta@aptiv.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@aptiv.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

On Tue, 8 Feb 2022 09:46:45 +0100, Oliver Barta wrote:
> From: Oliver Barta <oliver.barta@aptiv.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.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git for-linus

Thanks!

[1/1] regulator: core: fix false positive in regulator_late_cleanup()
      commit: 4e2a354e3775870ca823f1fb29bbbffbe11059a6

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark