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>
279428df88