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

On 25/02/2025 15:57, Fabrice Gasnier wrote:

On 2/25/25 13:02, Krzysztof Kozlowski wrote:

quoted

On Mon, Feb 24, 2025 at 07:01:43PM +0100, Fabrice Gasnier wrote:

quoted

   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