Re: [PATCH 1/2] dt-bindings: iio: light: Add AMS TCS3472 and TCS3400

[Krzysztof Kozlowski <krzk@kernel.org>]

On 17/10/2026 02:36, Jonathan Cameron wrote:
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - ams,tcs3400
>>> +      - ams,tcs3472  
>>
>> Your driver cod suggests these are compatible, so it should be expressed.
> 
> That's only true because this driver hard rejects a whoami mismatch
> which is something we shouldn't really be doing. If we do a look
> up in driver and fail to match we should be using the data associated with
> the ID that the fallback compatible would have had.
> 
> Our old fun of what should we do about fallback compatibles and
> devices with ID registers.  Some of which (in this driver) are actually
> compatible with each other and some of which are not (in the sense
> that the match the WHOAMI and do different things depending on that
> matching).
> 
> I still prefer that we never claim devices that need different
> handling are compatible (even if detectable) because of that prevents
> new drop in parts being used (as they normally have different whoami
> values even as supposedly drop in replacements).
> 
> I don't mind enough to argue much about it however.
> Note that before this series all the supported parts were actually
> compatible and the only difference was a print on the id match. So
> if this patch hadn't turned up an I'd noticed, I have simply
> deleted the error return.

In such case lack of compatibility should be very briefly explained in
the commit msg or description in binding.

Best regards,
Krzysztof