Re: Reading ADC that comes from a multiplexer

[Peter Rosin <peda@axentia.se>]

On 2021-09-22 16:20, Fabio Estevam wrote:
> Hi Peter,
> 
> On Wed, Sep 22, 2021 at 10:41 AM Fabio Estevam <festevam@gmail.com> wrote:
> 
>> but still the parent channel cannot be found.
>>
>> So I don't have the DT properly describing the ADC to the mux relationship yet.
> 
> It works fine now :-)
> 
> The trick was to change it like this:
> 
> -               stmpe_adc {
> +               adc0: stmpe_adc {
>                         compatible = "st,stmpe-adc";
>                         /* forbid to use ADC channels 3-0 (touch) */
>                         st,norequest-mask = <0x0F>;
> +                       #io-channel-cells = <1>;
>                 };
>         };
> 
> Thanks a lot!
> 

Nice!

While I don't completely understand that iio-device node in the beaglebone
dts that didn't work for you, it looks like it's just a renumbering thing?
However, your version only remapped 4 channels, and in that case your new
iio-device only had those, i.e. 0-3. But the iio-mux was looking for the
missing channel 4. Maybe that was why that variant didn't work?

So, yeah, copying the exynos4412-p4note was simpler.

Cheers,
Peter