Re: [PATCH 1/8] dt-bindings: mfd: stm32-lptimer: add support for stm32mp25

[Krzysztof Kozlowski <krzk@kernel.org>]

On 25/02/2025 15:57, Fabrice Gasnier wrote:
> On 2/25/25 13:02, Krzysztof Kozlowski wrote:
>> On Mon, Feb 24, 2025 at 07:01:43PM +0100, Fabrice Gasnier wrote:
>>>    pwm:
>>>      type: object
>>>      additionalProperties: false
>>>  
>>>      properties:
>>>        compatible:
>>> -        const: st,stm32-pwm-lp
>>> +        enum:
>>> +          - st,stm32-pwm-lp
>>> +          - st,stm32mp25-pwm-lp
>>>  
>>>        "#pwm-cells":
>>>          const: 3
>>> @@ -69,7 +76,9 @@ properties:
>>>  
>>>      properties:
>>>        compatible:
>>> -        const: st,stm32-lptimer-counter
>>> +        enum:
>>> +          - st,stm32-lptimer-counter
>>> +          - st,stm32mp25-lptimer-counter
>>
>> Driver changes suggest many of these are compatible. Why isn't this expressed?
> 
> Hi Krzysztof,
> 
> The Low Power Timer (LPTIM) hardware isn't fully backward compatible.
> 
> At driver level, as indicated in the cover-letter, same feature list as
> on STM32MP1x is supported currently. This is probably what makes it look
> like it's compatible, but it's not fully compatible.

I don't understand. Same feature list is supported means fully
compatible, but you say not fully compatible. You are aware that
compatible means not the same?

> 
> The hardware controller is a bit different. Some registers/bits has been
> revisited among other things. This is the purpose for these new compatibles.

We do not discuss new compatibles. We discuss lack of compatibility. If
registers/bits are changed, how existing driver can work with same ID table?



Best regards,
Krzysztof