Nicola Corna schrieb am 20.08.2015 um 16:11: > The maximum possible value for the relative humidity is 55575 (100%RH). > This value, if shifted right by 2 bits, uses 14 bits and masking it with > a 12 bit mask removes 2 meaningful bits. > The masking has been replaced with a range check that sets the minimum > value at 3194 (0%RH) and the maximum at 55575 (100%RH). Hmm, I guess the mask should have been applied for bits 13:2, but your solution confirms better to the data sheet. Just one essential detail: The raw sensor data has already been divided by 4 when you do the boundary check. So, you need to divide the boundaries, as well. Btw, you can make this a one-liner using clamp_val, check it out: [1] [1]http://lxr.free-electrons.com/source/include/linux/kernel.h#L795 > > Signed-off-by: Nicola Corna <nicola@xxxxxxxxxx> > --- > drivers/iio/humidity/si7020.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c > index fa3b809..62fdbcf 100644 > --- a/drivers/iio/humidity/si7020.c > +++ b/drivers/iio/humidity/si7020.c > @@ -57,8 +57,16 @@ static int si7020_read_raw(struct iio_dev *indio_dev, > if (ret < 0) > return ret; > *val = ret >> 2; > - if (chan->type == IIO_HUMIDITYRELATIVE) > - *val &= GENMASK(11, 0); > + /* > + * Humidity values can sligthly exceed the 0-100%RH > + * range and should be corrected by software > + */ > + if (chan->type == IIO_HUMIDITYRELATIVE) { > + if (*val < 3194) /* 0%RH */ > + *val = 3194; > + else if (*val > 55575) /* 100%RH */ > + *val = 55575; > + } > return IIO_VAL_INT; > case IIO_CHAN_INFO_SCALE: > if (chan->type == IIO_TEMP) > -- 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
