linux-kernel - [PATCH v2 1/4] iio: pressure: dps310: support negative temperature values

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Date: Wed, 10 Apr 2024 12:36:01 +0200
From: Thomas Haemmerle <thomas.haemmerle@...ca-geosystems.com>
To: joel@....id.au
Cc: bsp-development.geo@...ca-geosystems.com,
	Thomas Haemmerle <thomas.haemmerle@...ca-geosystems.com>,
	Eddie James <eajames@...ux.ibm.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/4] iio: pressure: dps310: support negative temperature values

The current implementation interprets negative values returned from
`dps310_calculate_temp` as error codes.
This has a side effect that when negative temperature values are
calculated, they are interpreted as error.

Fix this by using the return value only for error handling and passing a
pointer for the value.

Fixes: ba6ec48e76bc ("iio: Add driver for Infineon DPS310")
Signed-off-by: Thomas Haemmerle <thomas.haemmerle@...ca-geosystems.com>
---
 drivers/iio/pressure/dps310.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
index 1ff091b2f764..d0a516d56da4 100644
--- a/drivers/iio/pressure/dps310.c
+++ b/drivers/iio/pressure/dps310.c
@@ -730,7 +730,7 @@ static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
 	}
 }
 
-static int dps310_calculate_temp(struct dps310_data *data)
+static int dps310_calculate_temp(struct dps310_data *data, int *val)
 {
 	s64 c0;
 	s64 t;
@@ -746,7 +746,9 @@ static int dps310_calculate_temp(struct dps310_data *data)
 	t = c0 + ((s64)data->temp_raw * (s64)data->c1);
 
 	/* Convert to milliCelsius and scale the temperature */
-	return (int)div_s64(t * 1000LL, kt);
+	*val = (int)div_s64(t * 1000LL, kt);
+
+	return 0;
 }
 
 static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
@@ -768,11 +770,10 @@ static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
 		if (rc)
 			return rc;
 
-		rc = dps310_calculate_temp(data);
-		if (rc < 0)
+		rc = dps310_calculate_temp(data, val);
+		if (rc)
 			return rc;
 
-		*val = rc;
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
-- 
2.34.1