Re: [PATCH v2] iio: temperature: max30208: fix wrong scale value

[Salah Triki]

On Tue, Apr 28, 2026 at 07:02:16PM +0300, Andy Shevchenko wrote:
> On Tue, Apr 28, 2026 at 04:53:49PM +0100, Salah Triki wrote:
> > The driver currently returns a scale of 5 for IIO_CHAN_INFO_SCALE, which
> > leads to incorrect temperature readings.
> > 
> > According to the MAX30208 datasheet, the temperature resolution is 0.005°C
> > per LSB. Using IIO_VAL_FRACTIONAL with 5/1000 correctly represents this
> > 16-bit resolution.
> > 
> > Although this is a change in the ABI, the current scale is objectively
> > incorrect. A raw reading of 5000 (25°C) is currently reported as 25000°C,
> > making the driver unusable with standard IIO tools. Given the magnitude
> > of the error (factor of 1000) and the fact that the driver is relatively
> > recent, fixing it to match the hardware specification is necessary.
> 
> Seems the analysis is wrong (as per Jonathan's comment in v1). What are the
> user space tools you referring to?
> 
You are correct. My analysis was purely based on a misinterpretation of the
datasheet's resolution (0.005°C) versus the IIO ABI requirement for
temperature (milli-degrees).

I assumed the scale should convert raw values to Celsius directly, without
realizing that '5' was already the correct value in milli-degrees. Since I
don't have the hardware to verify the output, I relied solely on my reading
of the datasheet and missed the ABI unit convention.

I will withdraw this patch. Sorry for the confusion

Best regards
--
Salah Triki