Re: [PATCH] iio: afe: rescale: Fix logic bug

[Mighty <bavishimithil@gmail.com>]

On Mon, Aug 28, 2023 at 11:48 PM Jonathan Cameron <jic23@kernel.org> wrote:

> 2) If the channel has a horrible non linear and none invertable conversion
>    to standard units and events support the you might need PROCESSED to
>    provide the useful value, but RAW to give you clue what the current value
>    is for setting an event (light sensors are usual place we see this).

In this very specific case yes, it is being used as a current sense shunt for a light+prox sensor (gp2ap002), so I do think that it might be case 2 instead of 3. But with no other devices using the twl6030/32 gpadc for any features it could also be due to it not being updated like case 3. Also the fact that the adc would break in cases when its not just a light sensor as well, we just dont have any such devices yet.
I'm pretty lost at how the code handles RAW and PROCESSED anyways, cant seem to find a proper rescaler. Ideally BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) should be there in it, but since SCALE isnt used anywhere in the driver it wouldnt break any functionality, but it would lose logic. We'd have to look into the working of the gpadc again to understand how the factors fit in there.

Regards,
Mithil