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authorAlexandre Belloni <alexandre.belloni@free-electrons.com>2015-10-07 13:10:54 +0200
committerJonathan Cameron <jic23@kernel.org>2015-10-11 15:02:02 +0100
commitb94e22805a2224061bb263a82b72e09544a5fbb3 (patch)
tree54d1c2618d48a5d763da7d57cd34ab8e5690b9f9
parenteda7d0f38aaf50dbb2a2de15e8db386c4f6f65fc (diff)
iio: mxs-lradc: Fix temperature offset
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@elpromaelectronics.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Acked-by: Stefan Wahren <stefan.wahren@i2se.com> Acked-by: Marek Vasut <marex@denx.de> Cc: <stable@vger.kernel.org> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
-rw-r--r--drivers/staging/iio/adc/mxs-lradc.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
index 3f7715c9968b..47fc00a3f63b 100644
--- a/drivers/staging/iio/adc/mxs-lradc.c
+++ b/drivers/staging/iio/adc/mxs-lradc.c
@@ -915,11 +915,12 @@ 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;
}