From ed3730c435f1a9f9559ed7762035d22d8a95adfe Mon Sep 17 00:00:00 2001 From: Andreas Klinger Date: Mon, 10 Apr 2017 19:00:01 +0200 Subject: [PATCH] IIO: bmp280-core.c: fix error in humidity calculation While calculating the compensation of the humidity there are negative values interpreted as unsigned because of unsigned variables used. These values as well as the constants need to be casted to signed as indicated by the documentation of the sensor. Signed-off-by: Andreas Klinger Acked-by: Linus Walleij Reviewed-by: Matt Ranostay Cc: Signed-off-by: Jonathan Cameron --- drivers/iio/pressure/bmp280-core.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c index 4d18826ac63c..d82b788374b6 100644 --- a/drivers/iio/pressure/bmp280-core.c +++ b/drivers/iio/pressure/bmp280-core.c @@ -175,11 +175,12 @@ static u32 bmp280_compensate_humidity(struct bmp280_data *data, } H6 = sign_extend32(tmp, 7); - var = ((s32)data->t_fine) - 76800; - var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15) - * (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10) - + 2097152) * H2 + 8192) >> 14); - var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4; + var = ((s32)data->t_fine) - (s32)76800; + var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + + (s32)16384) >> 15) * (((((((var * H6) >> 10) + * (((var * (s32)H3) >> 11) + (s32)32768)) >> 10) + + (s32)2097152) * H2 + 8192) >> 14); + var -= ((((var >> 15) * (var >> 15)) >> 7) * (s32)H1) >> 4; return var >> 12; };