Re: [PATCH 2/3] iio: test: test gain-time-scale helpers

[Matti Vaittinen]

On 1/13/24 18:12, Jonathan Cameron wrote:
> On Wed, 10 Jan 2024 12:12:55 +0200
> Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
>
> > Some light sensors can adjust both the HW-gain and integration time.
> > There are cases where adjusting the integration time has similar impact
> > to the scale of the reported values as gain setting has.
> >
> > IIO users do typically expect to handle scale by a single writable 'scale'
> > entry. Driver should then adjust the gain/time accordingly.
> >
> > It however is difficult for a driver to know whether it should change
> > gain or integration time to meet the requested scale. Usually it is
> > preferred to have longer integration time which usually improves
> > accuracy, but there may be use-cases where long measurement times can be
> > an issue. Thus it can be preferable to allow also changing the
> > integration time - but mitigate the scale impact by also changing the gain
> > underneath. Eg, if integration time change doubles the measured values,
> > the driver can reduce the HW-gain to half.
> >
> > The theory of the computations of gain-time-scale is simple. However,
> > some people (undersigned) got that implemented wrong for more than once.
> > Hence some gain-time-scale helpers were introduced.
> >
> > Add some simple tests to verify the most hairy functions.
> >
> > Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
> Hi Matti,
>
> All seems reasonable to me. Some trivial formatting things inline
> + I'm not planning to check the maths as you are the expert in all of
> this so I'll just trust you!

Well, all checking is always welcome. Still, I kind of understand that 
you won't verify everything you see... Oh, and thanks for the trust. :)

> Also if this fails you get to pick up the pieces :)

This sure helps to trust ;)

As for things you commented - Thanks! I'll fix them and respin.

Yours,
	-- Matti

--
Matti Vaittinen
Linux kernel developer at ROHM Semiconductors
Oulu Finland

~~ When things go utterly wrong vim users can always type :help! ~~