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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>
This commit is contained in:
Alexandre Belloni 2015-10-07 13:10:54 +02:00 committed by Jonathan Cameron
parent eda7d0f38a
commit b94e22805a
1 changed files with 5 additions and 4 deletions
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9
drivers/staging/iio/adc/mxs-lradc.c
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@ -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;
}