linux-kernel - [PATCH] regulator: core: Fix enable GPIO reference counting

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Date:	Fri, 27 Feb 2015 11:41:03 -0800
From:	Doug Anderson <dianders@...omium.org>
To:	Mark Brown <broonie@...nel.org>
Cc:	milo.kim@...com, axel.lin@...ics.com,
	Dmitry Torokhov <dmitry.torokhov@...il.com>, olof@...om.net,
	javier.martinez@...labora.co.uk, Paul Stewart <pstew@...omium.org>,
	Doug Anderson <dianders@...omium.org>,
	<stable@...r.kernel.org>, lgirdwood@...il.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH] regulator: core: Fix enable GPIO reference counting

It is possible for _regulator_do_enable() to be called for an
already-enabled rdev, like in regulator_suspend_finish().  If we were
using an enable pin (rdev->ena_pin is set) then we'd end up
incrementing the reference count in regulator_ena_gpio_ctrl() over and
over again without a decrement.  That prevented the GPIO from going to
the "off" state even after all users were disabled.

Fix this by avoiding the call to regulator_ena_gpio_ctrl() when it's
not needed.

Signed-off-by: Doug Anderson <dianders@...omium.org>
Fixes: 967cfb18c0e3 ("regulator: core: manage enable GPIO list")
---
FYI: this was developed and tested against a 3.14 kernel with
backports; I've done basic boot testing against upstream and sanity
checked the code but haven't done as extensive testing there.

 drivers/regulator/core.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index b899947..9daccbb 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1839,10 +1839,12 @@ static int _regulator_do_enable(struct regulator_dev *rdev)
 	}
 
 	if (rdev->ena_pin) {
-		ret = regulator_ena_gpio_ctrl(rdev, true);
-		if (ret < 0)
-			return ret;
-		rdev->ena_gpio_state = 1;
+		if (!rdev->ena_gpio_state) {
+			ret = regulator_ena_gpio_ctrl(rdev, true);
+			if (ret < 0)
+				return ret;
+			rdev->ena_gpio_state = 1;
+		}
 	} else if (rdev->desc->ops->enable) {
 		ret = rdev->desc->ops->enable(rdev);
 		if (ret < 0)
@@ -1939,10 +1941,12 @@ static int _regulator_do_disable(struct regulator_dev *rdev)
 	trace_regulator_disable(rdev_get_name(rdev));
 
 	if (rdev->ena_pin) {
-		ret = regulator_ena_gpio_ctrl(rdev, false);
-		if (ret < 0)
-			return ret;
-		rdev->ena_gpio_state = 0;
+		if (rdev->ena_gpio_state) {
+			ret = regulator_ena_gpio_ctrl(rdev, false);
+			if (ret < 0)
+				return ret;
+			rdev->ena_gpio_state = 0;
+		}
 
 	} else if (rdev->desc->ops->disable) {
 		ret = rdev->desc->ops->disable(rdev);
-- 
2.2.0.rc0.207.ga3a616c

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