Re: [PATCH v3 1/2] dt-bindings: iio: dac: Add AD5529R

[David Lechner]

>>>>>    
>>>>>> But yes, I do feel that the whole feature is for aggregation so seeing
>>>>>> one device with 32 channels is the expectation here? Rather than seeing
>>>>>> two devices with 16 channels.
>>>>> Yes, I think aggregation is the whole point there... so that the IIO driver
>>>>> is multi-device-aware.
>>>> Which makes me feel that different pins per device might be possible
>>>> from an HW point of view but does not make much sense. For example, for
>>>> the buffer example I would expect LDAC to be shared between all the
>>>> devices.
>>> That is why I would still suggest the multi-dac node in the middle...
>>> the parent node can hold shared resources, while the dac children can
>>> have their own, overriding or inheriting stuff.
>>>
>> Before going down that path I'd want confirmation this is something we
>> actually think anyone will build.
>>
>> Jonathan
> 
> To directly answer your question- we currently do not have a platform that supports multi device topology with independent supplies or reset lines.
> Given that, I agree to start with the parallel wiring assumption and defer per chip resource variation under there is a solid use case. I will also drop the "adi,resolution" proposal and proceed with "adi,device-addrs" in the AD5529R binding.
> With all of the above, the proposed binding for the multi-device follow up series would look like:
> 
> 
>     dac@0 {
>         compatible = "adi,ad5529r-16";
>         reg = <0>;
>         adi,device-addrs = <0 1>;
>         reset-gpios = <&gpio0 87 GPIO_ACTIVE_LOW>;
>         vdd-supply  = <&vdd_reg>;
>         hvdd-supply = <&hvdd_reg>;
> 
>         channel@0  { reg = <0>;  adi,output-range-microvolt = <0 5000000>; };
>         channel@16 { reg = <16>; adi,output-range-microvolt = <0 40000000>; };
>     };
> 
> Does this look reasonable to everyone?
> 
> Regards,
> Janani Sunil
> 

LGTM. Seems like the simplest way to handle it and should cover most
use cases.