From: Nicolin Chen <nicoleotsuka@gmail.com>
Date: Wed, 14 Nov 2018 03:48:54 +0000 (-0800)
Subject: hwmon: (ina2xx) Fix current value calculation
X-Git-Tag: v4.4.168~76
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=15d8d7246173d11e7b75e34bc0226682468f9a8c;p=thirdparty%2Fkernel%2Fstable.git

hwmon: (ina2xx) Fix current value calculation

[ 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>
---

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 9ac6e16733750..1f291b344178a 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -273,7 +273,7 @@ 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: