[PATCH 1/8] dt-bindings: mfd: stm32-lptimer: add support for stm32mp25
Fabrice Gasnier
fabrice.gasnier at foss.st.com
Wed Feb 26 10:17:24 PST 2025
On 2/26/25 08:51, Krzysztof Kozlowski wrote:
> 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?
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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