Re: [bmp280 v1 3/6] iio: pressure: bmp280: implement sampling_frequency for BMx280

[ASSI <Stromeko@nexgo.de>]

Jonathan Cameron writes:
> Call it BMP280_ODR_MODE_FORCED rather than making it 0HZ related?
> Using the value 0 for the sysfs interface doesn't make much sense though.

Technically 0Hz is correct, though:  it dosn't cycle at all until we
tell it to do a single measurement.

> Even if it is a pain to work out, we should estimate what it means to
> use force mode wrt to how fast a single sample can be obtain.

MODE_FORCED just doesn't work well ffor devices that do mukltiple
measurements at once that then need to be read one by one.  At least not
by using the sysfs read request as the trigger for the measurement,
which is what the earlier patch did that went into v6.13

> It may be that is such that we don't bother with the other slow sampling
> frequency modes if they are slower as they aren't useful vs only reading
> when we want to.

The way these devices work is that you can read the result of the
last measurement as often as you want and in any order, even while
there's another measurement is in progress; and you can chose to have
free-running measurements or host triggered ones.  It's the current sysfs
implementation that enforces a rigidity that wasn't there before the
driver was changed to make the device sleep between measurements.


Regards,
Achim.
-- 
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