[PATCH 3.16.y-ckt 066/129] iio: pressure: mpl115: fix temperature offset sign
Luis Henriques
luis.henriques at canonical.com
Fri Feb 26 10:20:37 UTC 2016
3.16.7-ckt25 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Akinobu Mita <akinobu.mita at gmail.com>
commit 431386e783a3a6c8b7707bee32d18c353b8688b2 upstream.
According to the datasheet, the resolusion of temperature sensor is
-5.35 counts/C. Temperature ADC is 472 counts at 25C.
(https://www.sparkfun.com/datasheets/Sensors/Pressure/MPL115A1.pdf
NOTE: This is older revision, but this information is removed from the
latest datasheet from nxp somehow)
Temp [C] = (Tadc - 472) / -5.35 + 25
= (Tadc - 605.750000) * -0.186915888
So the correct offset is -605.750000.
Signed-off-by: Akinobu Mita <akinobu.mita at gmail.com>
Acked-by: Peter Meerwald-Stadler <pmeerw at pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23 at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/iio/pressure/mpl115.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/iio/pressure/mpl115.c b/drivers/iio/pressure/mpl115.c
index f5ecd6e19f5d..a0d7deeac62f 100644
--- a/drivers/iio/pressure/mpl115.c
+++ b/drivers/iio/pressure/mpl115.c
@@ -117,7 +117,7 @@ static int mpl115_read_raw(struct iio_dev *indio_dev,
*val = ret >> 6;
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
- *val = 605;
+ *val = -605;
*val2 = 750000;
return IIO_VAL_INT_PLUS_MICRO;
case IIO_CHAN_INFO_SCALE:
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