On Wed, May 30, 2018 at 03:20:37PM +0800, Matt Ranostay wrote: > On Wed, May 30, 2018 at 1:05 PM, Matt Ranostay > <matt.ranostay@xxxxxxxxxxxx> wrote: > > On Wed, May 30, 2018 at 9:17 AM, Phil Reid <preid@xxxxxxxxxxxxxxxxx> wrote: > >> On 30/05/2018 08:44, Matt Ranostay wrote: > >>> > >>> On Mon, May 28, 2018 at 11:38 PM, Tomasz Duszynski <tduszyns@xxxxxxxxx> > >>> wrote: > >>>> > >>>> According to IIO ABI relative humidity reading should be > >>>> returned in milli percent. > >>>> > >>>> This patch addresses that by applying proper scaling and > >>>> returning integer instead of fractional format type specifier. > >>>> > >>> > >>> *sigh* seems this is my mistake, but good catch. Slight nitpick > >>> below.. otherwise looks good > >>> > >>>> Signed-off-by: Tomasz Duszynski <tduszyns@xxxxxxxxx> > >>>> --- > >>>> drivers/iio/pressure/bmp280-core.c | 5 ++--- > >>>> 1 file changed, 2 insertions(+), 3 deletions(-) > >>>> > >>>> diff --git a/drivers/iio/pressure/bmp280-core.c > >>>> b/drivers/iio/pressure/bmp280-core.c > >>>> index 5ec3e41b65f2..fe87d27779d9 100644 > >>>> --- a/drivers/iio/pressure/bmp280-core.c > >>>> +++ b/drivers/iio/pressure/bmp280-core.c > >>>> @@ -415,10 +415,9 @@ static int bmp280_read_humid(struct bmp280_data > >>>> *data, int *val, int *val2) > >>>> } > >>>> comp_humidity = bmp280_compensate_humidity(data, adc_humidity); > >>>> > >>>> - *val = comp_humidity; > >>>> - *val2 = 1024; > >>>> + *val = comp_humidity * 1000 / 1024; > >>> > >>> > >>> Minor nitpick that it would look cleaner as: (comp_humidity / 1024) * > >>> 1000 > >>> > >> be careful of integer division. > >> > > > > Ah yes good point. You will have to check if comp_humidity isn't zero > > or it is possible to have a divide-by-zero. > > D'oh actually divide by zero would be an issue. But you'll want to be > sure of possible overflows (doubt that would be an issue here). What kind of division-by-zero are you meaning? When would that happen in this case? > > However it may be better to just add the scaling factor of 1000 with > IIO_CHAN_INFO_SCALE and make the processed value now a raw one. Is measurement precision your concern here? I would not bother with that since the sensor is not a top-notch anyway. Even datasheet itself specifies error margin of +/-3% for relative humidity. > > > > > - Matt > > > >> > >>>> > >>>> - return IIO_VAL_FRACTIONAL; > >>>> + return IIO_VAL_INT; > >>>> } > >>>> > >>>> static int bmp280_read_raw(struct iio_dev *indio_dev, > >>>> -- > >>>> 2.17.0 > >> > >> > >>> > >> > >> > >> -- > >> Regards > >> Phil Reid > >> -- 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
