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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,
        Iker Perez del Palomar Sustatxa 
        <iker.perez@codethink.co.uk>, Guenter Roeck <linux@roeck-us.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 190/271] hwmon: (lm75) Fix write operations for negative temperatures
Date:   Tue, 28 Jan 2020 15:05:39 +0100
Message-Id: <20200128135906.719278713@linuxfoundation.org>
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From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit 7d82fcc9d9e81241778aaa22fda7be753e237d86 ]

Writes into limit registers fail if the temperature written is negative.
The regmap write operation checks the value range, regmap_write accepts
an unsigned int as parameter, and the temperature value passed to
regmap_write is kept in a variable declared as long. Negative values
are converted large unsigned integers, which fails the range check.
Fix by type casting the temperature to u16 when calling regmap_write().

Cc: Iker Perez del Palomar Sustatxa <iker.perez@codethink.co.uk>
Fixes: e65365fed87f ("hwmon: (lm75) Convert to use regmap")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/lm75.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index eff3b24d84737..fc31669a86ba8 100644
--- a/drivers/hwmon/lm75.c
+++ b/drivers/hwmon/lm75.c
@@ -164,7 +164,7 @@ static int lm75_write(struct device *dev, enum hwmon_sensor_types type,
 	temp = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
 				 1000) << (16 - resolution);
 
-	return regmap_write(data->regmap, reg, temp);
+	return regmap_write(data->regmap, reg, (u16)temp);
 }
 
 static umode_t lm75_is_visible(const void *data, enum hwmon_sensor_types type,
-- 
2.20.1