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! ~~
