[PATCH 4.4 049/137] iio: pressure: mpl115: fix temperature offset sign

Greg Kroah-Hartman
2016-02-24T04:44:47Z

From: Akinobu Mita <akinobu.mita@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@gmail.com>
Acked-by: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/iio/pressure/mpl115.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iio/pressure/mpl115.c
+++ b/drivers/iio/pressure/mpl115.c
@@ -117,7 +117,7 @@ static int mpl115_read_raw(struct iio_de
*val = ret >> 6;
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
- *val = 605;
+ *val = -605;
*val2 = 750000;
return IIO_VAL_INT_PLUS_MICRO;