Linus Walleij <linus.walleij@xxxxxxxxxx>wrote:
> I have to do this change because my ADC driver only provides processed
> channels (drivers/iio/adc/ab8500-gpadc.c). It provides raw values and
> it provides processed values but no scale. That means your code will
> not work, sadly. It will result in the raw value being used without scaling.
> The reason that the ADC cannot provide scaling is that the scale is not
> linear and based on calibration. IIO scaling is only linear.
I haven't been able to find detailed documentation on the ab8500-gpadc,
so I have a couple of questions / comments:
1. The driver appears to support temperature output directly. Why do
you need ntc_thermistor?
2. I don't understand how the ab8500_gpadc_read_raw output of processed
data could possibly be correct.
if (mask == IIO_CHAN_INFO_PROCESSED) {
processed = ab8500_gpadc_ad_to_voltage(gpadc, ch->id, raw_val);
if (processed < 0)
return processed;
/* Return millivolt or milliamps or millicentigrades */
*val = processed * 1000;
return IIO_VAL_INT;
}
Note that both processed and *val are both of type int.
If *val really does end up with milliVolt units, then processed must
have had Volt units. And you only have single Volt resolution.
Either you are working with a lot higher voltages than I usually see,
or something must be wrong.
