[PATCH v2 2/2] hwmon: (pmbus/ina233) Handle sign extension for negative shunt voltage

[Pradhan, Sanman]

From: Sanman Pradhan <psanman@xxxxxxxxxxx>

ina233_read_word_data() reads MFR_READ_VSHUNT, which is a 16-bit
two's complement value. Because pmbus_read_word_data() returns an
integer, negative voltages (values > 32767) are currently treated as
large positive values, leading to incorrect scaling in DIV_ROUND_CLOSEST().

Add a cast to (s16) to ensure negative shunt voltages are correctly
sign-extended before the scaling calculation is performed.

Fixes: b64b6cb163f16 ("hwmon: Add driver for TI INA233 Current and Power Monitor")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sanman Pradhan <psanman@xxxxxxxxxxx>
---
v2:
  - Added (s16) cast to fix sign-extension for negative shunt voltages,
    complementing the error check fix applied in v1
---
 drivers/hwmon/pmbus/ina233.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/pmbus/ina233.c b/drivers/hwmon/pmbus/ina233.c
index dde1e16783943..819f4e8aeab61 100644
--- a/drivers/hwmon/pmbus/ina233.c
+++ b/drivers/hwmon/pmbus/ina233.c
@@ -70,7 +70,7 @@ static int ina233_read_word_data(struct i2c_client *client, int page,
 
 		/* Adjust returned value to match VIN coefficients */
 		/* VIN: 1.25 mV VSHUNT: 2.5 uV LSB */
-		ret = DIV_ROUND_CLOSEST(ret * 25, 12500);
+		ret = DIV_ROUND_CLOSEST((s16)ret * 25, 12500);
 		break;
 	default:
 		ret = -ENODATA;
-- 
2.34.1