Re: [PATCH 1/2] dt-bindings: pwm: clk-pwm: add optional GPIO and pinctrl properties

[Conor Dooley <conor@kernel.org>]

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On Mon, Apr 06, 2026 at 11:50:01PM +0800, Xilin Wu wrote:
> The clk-pwm driver cannot produce constant output levels (0% or 100%
> duty cycle, or disabled state) through the clock hardware alone - the
> actual pin level when the clock is off is undefined and
> hardware-dependent.
> 
> Document optional gpios, pinctrl-names, pinctrl-0, and pinctrl-1
> properties that allow the driver to switch the pin between clock
> function mux (for normal PWM output) and GPIO mode (to drive a
> deterministic constant level).
> 
> Signed-off-by: Xilin Wu <sophon@radxa.com>

This seems reasonable enough to me, but the PWM maintainers should
defintely make sure this fits the ideology of the device.
Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable

> ---
>  Documentation/devicetree/bindings/pwm/clk-pwm.yaml | 36 +++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/clk-pwm.yaml b/Documentation/devicetree/bindings/pwm/clk-pwm.yaml
> index ec1768291503..2a0e3e02d27b 100644
> --- a/Documentation/devicetree/bindings/pwm/clk-pwm.yaml
> +++ b/Documentation/devicetree/bindings/pwm/clk-pwm.yaml
> @@ -15,6 +15,11 @@ description: |
>    It's often possible to control duty-cycle of such clocks which makes them
>    suitable for generating PWM signal.
>  
> +  Optionally, a GPIO and pinctrl states can be provided. When a constant
> +  output level is needed (0%, 100%, or disabled), the pin is switched to
> +  GPIO mode to drive the level directly. For normal PWM output the pin is
> +  switched back to its clock function mux.
> +
>  allOf:
>    - $ref: pwm.yaml#
>  
> @@ -29,6 +34,26 @@ properties:
>    "#pwm-cells":
>      const: 2
>  
> +  gpios:
> +    description:
> +      Optional GPIO used to drive a constant level when the PWM output is
> +      disabled or set to 0% / 100% duty cycle. When provided, pinctrl states
> +      "default" (clock mux) and "gpio" must also be defined.
> +    maxItems: 1
> +
> +  pinctrl-names: true
> +
> +  pinctrl-0:
> +    description: Pin configuration for clock function mux (normal PWM).
> +    maxItems: 1
> +
> +  pinctrl-1:
> +    description: Pin configuration for GPIO mode (constant level output).
> +    maxItems: 1
> +
> +dependencies:
> +  gpios: [ pinctrl-0, pinctrl-1 ]
> +
>  unevaluatedProperties: false
>  
>  required:
> @@ -41,6 +66,15 @@ examples:
>        compatible = "clk-pwm";
>        #pwm-cells = <2>;
>        clocks = <&gcc 0>;
> -      pinctrl-names = "default";
> +    };
> +
> +  - |
> +    pwm {
> +      compatible = "clk-pwm";
> +      #pwm-cells = <2>;
> +      clocks = <&gcc 0>;
> +      pinctrl-names = "default", "gpio";
>        pinctrl-0 = <&pwm_clk_flash_default>;
> +      pinctrl-1 = <&pwm_clk_flash_gpio>;
> +      gpios = <&tlmm 32 0>;
>      };
> 
> -- 
> 2.53.0
> 

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