On Wed, May 30, 2018 at 10:23 PM, Tomasz Duszynski <tduszyns@xxxxxxxxx> wrote: > 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. As Phil mentioned the original patchset is okay as it is. Now I agree with him after thinking it through. Acked-by: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx> > >> >> > >> > - 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
