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iio: dac: ad5592r: fix temperature channel scaling value
commit279428df88
upstream. The scale value for the temperature channel is (assuming Vref=2.5 and the datasheet): 376.7897513 When calculating both val and val2 for the temperature scale we use (3767897513/25) and multiply it by Vref (here I assume 2500mV) to obtain: 2500 * (3767897513/25) ==> 376789751300 Finally we divide with remainder by 10^9 to get: val = 376 val2 = 789751300 However, we return IIO_VAL_INT_PLUS_MICRO (should have been NANO) as the scale type. So when converting the raw temperature value to the 'processed' temperature value we will get (assuming raw=810, offset=-753): processed = (raw + offset) * scale_val = (810 + -753) * 376 = 21432 processed += div((raw + offset) * scale_val2, 10^6) += div((810 + -753) * 789751300, 10^6) += 45015 ==> 66447 ==> 66.4 Celcius instead of the expected 21.5 Celsius. Fix this issue by changing IIO_VAL_INT_PLUS_MICRO to IIO_VAL_INT_PLUS_NANO. Fixes:56ca9db862
("iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs") Signed-off-by: Marc Ferland <marc.ferland@sonatest.com> Link: https://lore.kernel.org/r/20240501150554.1871390-1-marc.ferland@sonatest.com Cc: <Stable@vger.kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -415,7 +415,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
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s64 tmp = *val * (3767897513LL / 25LL);
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*val = div_s64_rem(tmp, 1000000000LL, val2);
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return IIO_VAL_INT_PLUS_MICRO;
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return IIO_VAL_INT_PLUS_NANO;
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}
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mutex_lock(&st->lock);
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