Re: [PATCH v3 09/10] dt-bindings: pinctrl: stm32: Support I/O synchronization parameters

[Conor Dooley <conor@kernel.org>]

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On Tue, Oct 14, 2025 at 04:04:50PM +0200, Antonio Borneo wrote:
> Document the support of the I/O synchronization parameters:
> - skew-delay-input;
> - skew-delay-output;
> - st,io-sync.
> 
> Forbid 'skew-delay-input' and 'skew-delay-output' to be both
> present on the same pin.
> Allow the new properties only with compatibles that support them.
> Add an example that uses the new properties.
> 
> Co-developed-by: Fabien Dessenne <fabien.dessenne@foss.st.com>
> Signed-off-by: Fabien Dessenne <fabien.dessenne@foss.st.com>
> Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
> ---
>  .../bindings/pinctrl/st,stm32-pinctrl.yaml    | 98 +++++++++++++++++++
>  1 file changed, 98 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
> index 2df141ed7222d..0010762127c05 100644
> --- a/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
> +++ b/Documentation/devicetree/bindings/pinctrl/st,stm32-pinctrl.yaml
> @@ -220,12 +220,89 @@ patternProperties:
>              minimum: 0
>              maximum: 3
>  
> +          skew-delay-input:
> +            description: |
> +              IO synchronization skew rate applied to the input path
> +              0: No delay
> +              1: Delay 0.30 ns
> +              2: Delay 0.50 ns
> +              3: Delay 0.75 ns
> +              4: Delay 1.00 ns
> +              5: Delay 1.25 ns
> +              6: Delay 1.50 ns
> +              7: Delay 1.75 ns
> +              8: Delay 2.00 ns
> +              9: Delay 2.25 ns
> +              10: Delay 2.50 ns
> +              11: Delay 2.75 ns
> +              12: Delay 3.00 ns
> +              13: Delay 3.25 ns
> +            minimum: 0
> +            maximum: 13
> +
> +          skew-delay-output:
> +            description: |
> +              IO synchronization latch delay applied to the output path
> +              0: No delay
> +              1: Delay 0.30 ns
> +              2: Delay 0.50 ns
> +              3: Delay 0.75 ns
> +              4: Delay 1.00 ns
> +              5: Delay 1.25 ns
> +              6: Delay 1.50 ns
> +              7: Delay 1.75 ns
> +              8: Delay 2.00 ns
> +              9: Delay 2.25 ns
> +              10: Delay 2.50 ns
> +              11: Delay 2.75 ns
> +              12: Delay 3.00 ns
> +              13: Delay 3.25 ns
> +            minimum: 0
> +            maximum: 13

Same comments here as on the earlier patch. I would like to see times
used natively.
pw-bot: changes-requested

> +
> +          st,io-sync:
> +            description: |
> +              IO synchronization through re-sampling or inversion
> +              0: data or clock GPIO pass-through
> +              1: clock GPIO inverted
> +              2: data GPIO re-sampled on clock rising edge
> +              3: data GPIO re-sampled on clock falling edge
> +              4: data GPIO re-sampled on both clock edges
> +            $ref: /schemas/types.yaml#/definitions/uint32
> +            enum: [0, 1, 2, 3, 4]

I really don't like this kinds of properties that lead to "random"
numbers in devicetree. I'd much rather see a string list here.

> +
>          required:
>            - pinmux
>  
> +        # Not allowed both skew-delay-input and skew-delay-output
> +        if:
> +          required:
> +            - skew-delay-input
> +        then:
> +          properties:
> +            skew-delay-output: false
> +
>  allOf:
>    - $ref: pinctrl.yaml#
>  
> +  - if:
> +      not:
> +        properties:
> +          compatible:
> +            contains:
> +              enum:
> +                - st,stm32mp257-pinctrl
> +                - st,stm32mp257-z-pinctrl
> +    then:
> +      patternProperties:
> +        '-[0-9]*$':
> +          patternProperties:
> +            '^pins':
> +              properties:
> +                skew-delay-input: false
> +                skew-delay-output: false
> +                st,io-sync: false
> +
>  required:
>    - compatible
>    - '#address-cells'
> @@ -306,4 +383,25 @@ examples:
>                  pinctrl-names = "default";
>      };
>  
> +  - |
> +    #include <dt-bindings/pinctrl/stm32-pinfunc.h>
> +    //Example 4 skew-delay and st,io-sync
> +      pinctrl: pinctrl@44240000 {
> +              compatible = "st,stm32mp257-pinctrl";
> +              #address-cells = <1>;
> +              #size-cells = <1>;
> +              ranges = <0 0x44240000 0xa0400>;
> +
> +              eth3_rgmii_pins_a: eth3-rgmii-0 {
> +                      pins1 {
> +                              pinmux = <STM32_PINMUX('A', 6, AF14)>;
> +                              st,io-sync = <4>;
> +                      };
> +                      pins2 {
> +                              pinmux = <STM32_PINMUX('H', 2, AF14)>;
> +                              skew-delay-output = <2>;
> +                      };
> +              };
> +      };
> +
>  ...
> -- 
> 2.34.1
> 

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