linux-kernel - Re: [PATCH v10 1/9] dt-bindings: regulator: Document MediaTek MT6316 PMIC Regulators

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Message-ID: <20251024-think-handwoven-504634ca620d@spud>
Date: Fri, 24 Oct 2025 17:29:31 +0100
From: Conor Dooley <conor@...nel.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: linux-mediatek@...ts.infradead.org, lee@...nel.org, robh@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org, matthias.bgg@...il.com,
	lgirdwood@...il.com, broonie@...nel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	kernel@...labora.com, wenst@...omium.org,
	igor.belwon@...tallysanemainliners.org
Subject: Re: [PATCH v10 1/9] dt-bindings: regulator: Document MediaTek MT6316
 PMIC Regulators

On Fri, Oct 24, 2025 at 10:32:13AM +0200, AngeloGioacchino Del Regno wrote:
> Add bindings for the regulators found in the MediaTek MT6316 PMIC,
> usually found in board designs using the MT6991 Dimensity 9400 and
> on MT8196 Kompanio SoC for Chromebooks.
> 
> This chip is fully controlled by SPMI and has multiple variants
> providing different phase configurations.
> 
> Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>  .../regulator/mediatek,mt6316b-regulator.yaml | 78 +++++++++++++++++++
>  .../regulator/mediatek,mt6316c-regulator.yaml | 78 +++++++++++++++++++
>  .../regulator/mediatek,mt6316d-regulator.yaml | 77 ++++++++++++++++++
>  3 files changed, 233 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/regulator/mediatek,mt6316b-regulator.yaml
>  create mode 100644 Documentation/devicetree/bindings/regulator/mediatek,mt6316c-regulator.yaml
>  create mode 100644 Documentation/devicetree/bindings/regulator/mediatek,mt6316d-regulator.yaml
> 
> diff --git a/Documentation/devicetree/bindings/regulator/mediatek,mt6316b-regulator.yaml b/Documentation/devicetree/bindings/regulator/mediatek,mt6316b-regulator.yaml
> new file mode 100644
> index 000000000000..65b70dd90728
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/regulator/mediatek,mt6316b-regulator.yaml
> @@ -0,0 +1,78 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/regulator/mediatek,mt6316b-regulator.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek MT6316 BP/VP SPMI PMIC Regulators
> +
> +maintainers:
> +  - AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> +
> +description:
> +  The MediaTek MT6316BP/VP PMICs are fully controlled by SPMI interface, both
> +  feature four step-down DC/DC (buck) converters, and provides 2+2 Phases,
> +  joining Buck 1+2 for the first phase, and Buck 3+4 for the second phase.
> +
> +properties:
> +  compatible:
> +    const: mediatek,mt6316b-regulator
> +
> +  reg:
> +    maxItems: 1
> +
> +patternProperties:
> +  "^vbuck(12|34)$":
> +    type: object
> +    $ref: regulator.yaml#
> +    unevaluatedProperties: false
> +    properties:
> +      regulator-allowed-modes:
> +        description: |
> +          Allowed Buck regulator operating modes allowed. Valid values below.
> +            0 - Normal mode with automatic power saving, reducing the switching
> +                frequency when light load conditions are detected
> +            1 - Forced Continuous Conduction mode (FCCM) for improved voltage
> +                regulation accuracy with constant switching frequency but lower
> +                regulator efficiency
> +            2 - Forced Low Power mode for improved regulator efficiency, used
> +                when no heavy load is expected, will shut down unnecessary IP
> +                blocks and secondary phases to reduce quiescent current.
> +                This mode does not limit the maximum output current but unless
> +                only a light load is applied, there will be regulation accuracy
> +                and efficiency losses.
> +        minItems: 1
> +        maxItems: 3
> +        items:
> +          enum: [ 0, 1, 2 ]

This property has no default, and the property is not required. Is one
of these modes the default, or is there another mode beyond what's here
that is used if the property is absent? Or are all modes allowed with no
property?

> +
> +required:
> +  - compatible
> +  - reg
> +  - '#address-cells'

Why is address-cells required here? Your bucks don't have addresses.
If it is actually required, Rob's bot has pointed out that the property
isn't defined for the device anyway.

pw-bot: changes-requested

> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/spmi/spmi.h>
> +
> +    spmi {
> +      #address-cells = <2>;
> +      #size-cells = <0>;
> +
> +      pmic@8 {
> +        compatible = "mediatek,mt6316b-regulator";
> +        reg = <0x8 SPMI_USID>;
> +        #address-cells = <0>;
> +
> +        vbuck12 {
> +          regulator-name = "dvdd_core";
> +          regulator-min-microvolt = <450000>;
> +          regulator-max-microvolt = <965000>;
> +          regulator-allowed-modes = <0 1 2>;
> +          regulator-enable-ramp-delay = <256>;
> +        };
> +      };
> +    };
> +...

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