Re: [PATCH] hwmon: (ntc_thermistor): try reading processed

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First, let me apologize if some of you may have received an
earlier version as HTML.

I forgot that I was in my web email client.


On 12/23/20 3:08 PM, Linus Walleij wrote:
Then commit 0315253b19bbc63eedad2f6125c21e280c76e29b
"hwmon: (ntc_thermistor) fix iio raw to microvolts conversion"
calls iio_convert_raw_to_processed() to get around the 12
bit assumption, instead adding a 1000x scale assumption
on the value passed in from the raw read. This just looks
wrong, why would it be 1000 and not 1 like the IIO core does
when we call iio_read_channel_processed()? It looks like it is
actually compensating for a bug in the ADC returning
the wrong scale: the author may have used a buggy ADC
driver return a scaling to volts instead of millivolts and then this
was a trial-and-error solution to that bug in the ADC
driver.

In that case it would be nice to know which ADC driver,
so we can fix it! I suspect maybe an out-of-tree ADC?

I'm the author ofcommit 0315253b19bbc63eedad2f6125c21e280c76e29b
"hwmon: (ntc_thermistor) fix iio raw to microvolts conversion".

The 1000X scaling was not to get around a bad ADC driver that returns
volts instead of millivolts; it was to convert millivolts to microvolts.
The function ntc_adc_iio_read needs to return microvolts.




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