On Mon, Nov 06, 2023 at 11:32:48AM +0100, Jerome Brunet wrote:
> s4 has been added to the compatible list while converting the Amlogic PWM
> binding documentation from txt to yaml.
>
> However, on the s4, the clock bindings have different meaning compared to
> previous SoCs.
>
> On previous SoCs the clock bindings used to describe which input the PWM
> channel multiplexer should pick among its possible parents.
>
> This is very much tied to the driver implementation, instead of describing
> the HW for what it is. When support for the Amlogic PWM was first added,
> how to deal with clocks through DT was not as clear as it nowadays.
> The Linux driver now ignores this DT setting, but still relies on the
> hard-coded list of clock sources.
>
> On the s4, the input multiplexer is gone. The clock bindings actually
> describe the clock as it exists, not a setting. The property has a
> different meaning, even if it is still 2 clocks and it would pass the check
> when support is actually added.
>
> Also the s4 cannot work if the clocks are not provided, so the property no
> longer optional.
>
> Finally, for once it makes sense to see the input as being numbered
> somehow. No need to bother with clock-names on the s4 type of PWM.
>
> Fixes: 43a1c4ff3977 ("dt-bindings: pwm: Convert Amlogic Meson PWM binding")
> Signed-off-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
> ---
> .../devicetree/bindings/pwm/pwm-amlogic.yaml | 68 ++++++++++++++++---
> 1 file changed, 59 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> index 527864a4d855..754b70fc2db0 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> +++ b/Documentation/devicetree/bindings/pwm/pwm-amlogic.yaml
> @@ -9,9 +9,6 @@ title: Amlogic PWM
> maintainers:
> - Heiner Kallweit <hkallweit1@xxxxxxxxx>
>
> -allOf:
> - - $ref: pwm.yaml#
> -
> properties:
> compatible:
> oneOf:
> @@ -43,12 +40,8 @@ properties:
> maxItems: 2
>
> clock-names:
> - oneOf:
> - - items:
> - - enum: [clkin0, clkin1]
> - - items:
> - - const: clkin0
> - - const: clkin1
> + minItems: 1
> + maxItems: 2
>
> "#pwm-cells":
> const: 3
> @@ -57,6 +50,56 @@ required:
> - compatible
> - reg
>
> +allOf:
> + - $ref: pwm.yaml#
> +
> + - if:
> + properties:
> + compatible:
> + contains:
> + enum:
> + - amlogic,meson8-pwm
> + - amlogic,meson8b-pwm
> + - amlogic,meson-gxbb-pwm
> + - amlogic,meson-gxbb-ao-pwm
> + - amlogic,meson-axg-ee-pwm
> + - amlogic,meson-axg-ao-pwm
> + - amlogic,meson-g12a-ee-pwm
> + - amlogic,meson-g12a-ao-pwm-ab
> + - amlogic,meson-g12a-ao-pwm-cd
> + - amlogic,meson-gx-pwm
> + - amlogic,meson-gx-ao-pwm
> + then:
> + # Historic bindings tied to the driver implementation
> + # The clocks provided here are meant to be matched with the input
> + # known (hard-coded) in the driver and used to select pwm clock
> + # source. Currently, the linux driver ignores this.
> + properties:
> + clock-names:
> + oneOf:
> + - items:
> + - enum: [clkin0, clkin1]
> + - items:
> + - const: clkin0
> + - const: clkin1
> +
> + # Newer IP block take a single input per channel, instead of 4 inputs
> + # for both channels
> + - if:
> + properties:
> + compatible:
> + contains:
> + enum:
> + - amlogic,meson-s4-pwm
> + then:
> + properties:
> + clocks:
> + items:
> + - description: input clock of PWM channel A
> + - description: input clock of PWM channel B
> + required:
> + - clocks
What are the 'clock-names' in this case? Because it's still allowed.
Rob
