Re: run-time change of configuration of ad74412

["Nuno Sá" <noname.nuno@gmail.com>]

On Fri, 2022-12-02 at 12:16 +0100, Rasmus Villemoes wrote:
> Hi,
> 
> My customer wants to be able to change the configuration of the four
> channels of the ad74412 at run-time; their board can be used in
> various
> scenarios, and having to specify the functions in device tree is too
> inflexible.
> 
> Is there any precedent in other iio drivers for such a configuration
> change, and/or is it feasible to implement this in the ad74413r.c
> driver?
> 
> I do not need to be able to change it continuously, just once after
> userspace has come up and before anything actually starts making use
> of
> the device, but it is not possible for me to know the correct
> configuration in the bootloader, so having U-Boot patch the dtb is
> not
> an option. A somewhat hacky way would be to build the driver as a
> module, and allow module parameter(s) to overrule whatever is in
> devicetree, but that doesn't really work if there was more than one
> ad74412/ad74413 present, unless one invents and parses some weird
> syntax
> to have certain settings apply to $this-chipselect on $that-bus.
> 
> Rasmus

Hi Rasmus,

I did not looked too deep into this but from what you described it
sounds like a nasty hack that I'm not sure if it's feasable... Would
devicetree overlays be an option for you? Some userspace daemon could
decide which one to load depending on the usecase?

- Nuno Sá