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From: Sasha Levin <sashal@kernel.org>
To: stable@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Nicolin Chen <nicoleotsuka@gmail.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Sasha Levin <sashal@kernel.org>,
	linux-hwmon@vger.kernel.org
Subject: [PATCH AUTOSEL 4.14 13/69] hwmon: (ina2xx) Fix current value calculation
Date: Wed,  5 Dec 2018 04:41:51 -0500	[thread overview]
Message-ID: <20181205094247.6556-13-sashal@kernel.org> (raw)
In-Reply-To: <20181205094247.6556-1-sashal@kernel.org>

From: Nicolin Chen <nicoleotsuka@gmail.com>

[ Upstream commit 38cd989ee38c16388cde89db5b734f9d55b905f9 ]

The current register (04h) has a sign bit at MSB. The comments
for this calculation also mention that it's a signed register.

However, the regval is unsigned type so result of calculation
turns out to be an incorrect value when current is negative.

This patch simply fixes this by adding a casting to s16.

Fixes: 5d389b125186c ("hwmon: (ina2xx) Make calibration register value fixed")
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hwmon/ina2xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index c2252cf452f5..07ee19573b3f 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -274,7 +274,7 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg,
 		break;
 	case INA2XX_CURRENT:
 		/* signed register, result in mA */
-		val = regval * data->current_lsb_uA;
+		val = (s16)regval * data->current_lsb_uA;
 		val = DIV_ROUND_CLOSEST(val, 1000);
 		break;
 	case INA2XX_CALIBRATION:
-- 
2.17.1

  parent reply	other threads:[~2018-12-05  9:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20181205094247.6556-1-sashal@kernel.org>
2018-12-05  9:41 ` [PATCH AUTOSEL 4.14 10/69] hwmon (ina2xx) Fix NULL id pointer in probe() Sasha Levin
2018-12-05  9:41 ` Sasha Levin [this message]
2018-12-05  9:41 ` [PATCH AUTOSEL 4.14 18/69] hwmon: (w83795) temp4_type has writable permission Sasha Levin

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