Re: [RFC 6/9] iio: ina2xx: add direct IO support for TI INA2xx Power Monitors

[Marc Titinger]

On 21/11/2015 19:13, Jonathan Cameron wrote:
> On 18/11/15 14:38, Marc Titinger wrote:
> > Basic support or direct IO raw read, with averaging attribute.
> > Values are RAW, INT_PLUS_MICRO (Volt/Ampere/Watt).
> >
> > Output of iio_info:
> >
> >       iio:device0: ina226
> >        4 channels found:
> >          power3:  (input)
> >          1 channel-specific attributes found:
> >                  attr 0: raw value: 1.150000
> >          voltage0:  (input)
> >          1 channel-specific attributes found:
> >                  attr 0: raw value: 0.000003
> >          voltage1:  (input)
> >          1 channel-specific attributes found:
> >                  attr 0: raw value: 4.277500
> >          current2:  (input)
> >          1 channel-specific attributes found:
> >                  attr 0: raw value: 0.268000
> >          4 device-specific attributes found:
> >                  attr 0: sampling_frequency_available value: 61 120 236...
> >                  attr 1: in_averaging_steps value: 4
> >                  attr 2: in_calibscale value: 10000
> >                  attr 3: in_sampling_frequency value: 1506
> >
> > Tested with ina226, on BeagleBoneBlack.
> >
> > Datasheet: http://www.ti.com/lit/gpn/ina226
> >
> > Signed-off-by: Marc Titinger <mtitinger@xxxxxxxxxxxx>
> You have added some new ABI in here, but I'm not seeing any documentation
> for averaging_steps.  Does this map onto the existing oversampling_ratio?

I am not sure normal averaging maps well with oversampling. Normal 
averaging will provide one value every N samples (this is what this chip 
does), while oversampling will interpolate N value between sample 'k' 
and 'k-1', and decimate to provide a less-noisy version of sample 'k', 
the resulting sampling frequency is not lower.



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