On Sun, Sep 27, 2015 at 6:29 AM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > On 27/09/15 07:18, Matt Ranostay wrote: >> Previous offset wasn't applied in the correct order and invalid. >> This patchset fixes this issue, and also has the correct scale value >> applied to the offset. >> >> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx> > Oops, missed that. > > Given it's provided in the datasheet as effectively a fractional value > would val = -40000, val2 = 65536 and type = IIO_FRACTIONAL not be cleaner > and give the same answer? > Actually not because the way the datasheet states it ((value / 2**16) * 165) - 40, so the scale value needs to be applied to the -40 offset (165/65536) > Speaking of which, for the scale are we loosing any precision by shifting > the bottom of the fraction right 2 rather than the top left 2 which would have > the same result? Ah possibly. But I suspect isn't anything measurable... > > Jonathan >> --- >> drivers/iio/humidity/hdc100x.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/iio/humidity/hdc100x.c b/drivers/iio/humidity/hdc100x.c >> index 2824578..a7f61e8 100644 >> --- a/drivers/iio/humidity/hdc100x.c >> +++ b/drivers/iio/humidity/hdc100x.c >> @@ -221,8 +221,9 @@ static int hdc100x_read_raw(struct iio_dev *indio_dev, >> } >> break; >> case IIO_CHAN_INFO_OFFSET: >> - *val = -40; >> - return IIO_VAL_INT; >> + *val = -3971; >> + *val2 = 879096; >> + return IIO_VAL_INT_PLUS_MICRO; >> default: >> return -EINVAL; >> } >> > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
