Thread (29 messages) 29 messages, 4 authors, 2025-03-05

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

From: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Date: 2025-02-26 20:25:11
Also in: linux-devicetree, linux-iio, linux-pwm, lkml

On 2/26/25 08:51, Krzysztof Kozlowski wrote:
On 25/02/2025 15:57, Fabrice Gasnier wrote:
quoted
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?
quoted
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?
Hi Krzysztof,

To summarize on dt-bindings side, here is my view, following your
comments on per driver basis of the compatible usage.

Let's keep these new compatibles:
- "st,stm32mp25-lptimer-trigger"
- "st,stm32mp25-lptimer-counter"

Both reflect not only LPTimer hardware update, but also specific
interconnect to other hardware blocks throughout all the STM32MP25 SoC.

Other compatible strings may be dropped. Reading the
revision/identification register of the LPTimer should be enough for
compatibility in the related drivers.

I'll update this in next revision of the series.

Thanks for reviewing,
Best Regards,
Fabrice


Best regards,
Krzysztof
  
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