From: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit b94e22805a2224061bb263a82b72e09544a5fbb3 ]
0° Kelvin is actually −273.15°C, not -272.15°C. Fix the temperature offset.
Also improve the comment explaining the calculation.
Reported-by: Janusz Użycki <j.uzycki@xxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Acked-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Acked-by: Marek Vasut <marex@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <jic23@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
drivers/staging/iio/adc/mxs-lradc.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index ffd4207..6050c58 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -910,11 +910,12 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
case IIO_CHAN_INFO_OFFSET:
if (chan->type == IIO_TEMP) {
/* The calculated value from the ADC is in Kelvin, we
- * want Celsius for hwmon so the offset is
- * -272.15 * scale
+ * want Celsius for hwmon so the offset is -273.15
+ * The offset is applied before scaling so it is
+ * actually -213.15 * 4 / 1.012 = -1079.644268
*/
- *val = -1075;
- *val2 = 691699;
+ *val = -1079;
+ *val2 = 644268;
return IIO_VAL_INT_PLUS_MICRO;
}
--
2.5.0
--
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