linux-kernel - Re: [PATCH v1 1/3] dt-bindings: pwm: Add binding for Allwinner D1/T113-S3/R329 PWM controller

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Date:   Thu, 15 Jun 2023 17:37:15 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Aleksandr Shubin <privatesub2@...il.com>
Cc:     linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
        Maxime Ripard <mripard@...nel.org>, linux-pwm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v1 1/3] dt-bindings: pwm: Add binding for Allwinner
 D1/T113-S3/R329 PWM controller

Hey Aleksandr,

On Thu, Jun 15, 2023 at 05:43:56PM +0300, Aleksandr Shubin wrote:
> Allwinner's D1, T113-S3 and R329 SoCs have a new pwm
> controller witch is different from the previous pwm-sun4i.
> 
> D1 and T113s SoCs have one PWM controller with 8 channels.
> R329 SoC has two PWM controllers in both power domains, one of
> them has 9 channels (CPUX one) and the other has 6 (CPUS one).

It would be good to note that the D1 and T113 are identical in terms of
peripherals, they differ only in the architecture of the CPU core, and
even share the majority of their DT. Because of that, using the same
compatible makes sense.
The R329 is a different SoC though, and should have a different
compatible string added, especially as there is a difference in the
number of channels. It would be fine to use the current compatible for
the D1 as a fallback.
The allwinner,pwm-channels property should probably only be allowed on
the R329 and only allow the values of 6 & 9.

> Add a device tree binding for them.
> 
> Signed-off-by: Aleksandr Shubin <privatesub2@...il.com>
> ---
>  .../bindings/pwm/allwinner,sun20i-pwm.yaml    | 70 +++++++++++++++++++
>  1 file changed, 70 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml
> 
> diff --git a/Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml b/Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml
> new file mode 100644
> index 000000000000..e5f9cb2d5c4f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/allwinner,sun20i-pwm.yaml
> @@ -0,0 +1,70 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pwm/allwinner,sun20i-pwm.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Allwinner D1, T113-S3 and R329 PWM
> +
> +maintainers:
> +  - Chen-Yu Tsai <wens@...e.org>
> +  - Maxime Ripard <mripard@...nel.org>

BTW, this should probably be you, since you have the hardware with this
SoC.

> +
> +allOf:
> +  - $ref: pwm.yaml#
> +
> +properties:
> +  compatible:
> +    const: allwinner,sun20i-d1-pwm
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#pwm-cells":
> +    const: 3
> +
> +  clocks:
> +    items:
> +      - description: 24 MHz oscillator
> +      - description: Bus Clock
> +
> +  clock-names:
> +    items:
> +      - const: hosc
> +      - const: bus
> +
> +  resets:
> +    items:
> +      - description: module reset

Don't need the items here, because there is only one. You can just do
"maxItems: 1" instead.

> +  allwinner,pwm-channels:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: The number of PWM channels configured for this instance
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#pwm-cells"
> +  - clocks
> +  - clock-names
> +  - resets
> +  - allwinner,pwm-channels

Cheers,
Conor.

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