linux-kernel - [PATCH] hwmon: da9052: Synchronize access with mfd

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Message-Id: <20200511110219.68188-1-sebastian.reichel@collabora.com>
Date:   Mon, 11 May 2020 13:02:19 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Support Opensource <support.opensource@...semi.com>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>
Cc:     Lee Jones <lee.jones@...aro.org>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...labora.com,
        Samu Nuutamo <samu.nuutamo@...cit.fi>,
        Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: [PATCH] hwmon: da9052: Synchronize access with mfd

From: Samu Nuutamo <samu.nuutamo@...cit.fi>

When tsi-as-adc is configured it is possible for in7[0123]_input read to
return an incorrect value if a concurrent read to in[456]_input is
performed. This is caused by a concurrent manipulation of the mux
channel without proper locking as hwmon and mfd use different locks for
synchronization.

Switch hwmon to use the same lock as mfd when accessing the TSI channel.

Fixes: 4f16cab19a3d5 ("hwmon: da9052: Add support for TSI channel")
Signed-off-by: Samu Nuutamo <samu.nuutamo@...cit.fi>
[rebase to current master, reword commit message slightly]
Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.com>
---
 drivers/hwmon/da9052-hwmon.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/da9052-hwmon.c b/drivers/hwmon/da9052-hwmon.c
index 53b517dbe7e6..4af2fc309c28 100644
--- a/drivers/hwmon/da9052-hwmon.c
+++ b/drivers/hwmon/da9052-hwmon.c
@@ -244,9 +244,9 @@ static ssize_t da9052_tsi_show(struct device *dev,
 	int channel = to_sensor_dev_attr(devattr)->index;
 	int ret;
 
-	mutex_lock(&hwmon->hwmon_lock);
+	mutex_lock(&hwmon->da9052->auxadc_lock);
 	ret = __da9052_read_tsi(dev, channel);
-	mutex_unlock(&hwmon->hwmon_lock);
+	mutex_unlock(&hwmon->da9052->auxadc_lock);
 
 	if (ret < 0)
 		return ret;
-- 
2.26.2