Date:   Thu, 16 Feb 2023 17:57:14 +0800
From:   ChiYuan Huang <cy_huang@richtek.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
CC:     <broonie@kernel.org>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <lgirdwood@gmail.com>,
        <u0084500@gmail.com>, <linux-kernel@vger.kernel.org>,
        <devicetree@vger.kernel.org>
Subject: Re: [PATCH 1/2] dt-bindings: regulator: Add bindings for Richtek
 RT5739
Message-ID: <20230216095714.GA14578@linuxcarl2.richtek.com>
References: <1676426457-1389-1-git-send-email-cy_huang@richtek.com>
 <1676426457-1389-2-git-send-email-cy_huang@richtek.com>
 <9c1f4d0e-83c9-014e-bdb1-38b4b0fb2bbf@linaro.org>
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On Thu, Feb 16, 2023 at 10:12:15AM +0100, Krzysztof Kozlowski wrote:
> On 15/02/2023 03:00, cy_huang@richtek.com wrote:
> > From: ChiYuan Huang <cy_huang@richtek.com>
> > 
> > Add the binding document for Richtek RT5739.
> 
> Subject: drop second/last, redundant "bindings for". The "dt-bindings"
> prefix is already stating that these are bindings.
>
Then, refine it to "dt-bindings: regulator: Add Richtek RT5739 document" 
> > 
> > Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> > ---
> >  .../bindings/regulator/richtek,rt5739.yaml         | 80 ++++++++++++++++++++++
> >  1 file changed, 80 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/regulator/richtek,rt5739.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/regulator/richtek,rt5739.yaml b/Documentation/devicetree/bindings/regulator/richtek,rt5739.yaml
> > new file mode 100644
> > index 00000000..7dc4f78
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/regulator/richtek,rt5739.yaml
> > @@ -0,0 +1,80 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/regulator/richtek,rt5739.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Richtek RT5739 2.4MHz 3.5A Step-Down Converter
> > +
> > +maintainers:
> > +  - ChiYuan Huang <cy_huang@richtek.com>
> > +
> > +description: |
> > +  The RT5739 is a step-down switching voltage regulator that delivers a
> > +  digitally programmable output from an input voltage supply of 2.5V to 5.5V.
> > +  The output voltage is programmed through an I2C interface capable of
> > +  operating up to 3.4MHz.
> > +
> > +  Using a proprietary architecture with synchronous rectification, the RT5739
> > +  is capable of delivering 3.5A continuously at over 80% efficiency,
> > +  maintaining that efficiency at load current as low as 10mA. The regulator
> > +  operates at a normal fixed frequency of 2.4MHz, which reduces the value of
> > +  the external components. 
> 
> Can we drop the marketing from kernel? Last part of sentence is not
> related to this submission at all. The internal frequency also looks
> unrelated to the topic...
>
Okay, too much marketing text. I'll shorten it and simply describe the function or
voltage range only. 
> > Additional output capacitance can be added to
> > +  improve regulation during load transients without affecting stability.
> > +
> > +allOf:
> > +  - $ref: regulator.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - richtek,rt5739
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  enable-gpios:
> > +    maxItems: 1
> > +
> > +  richtek,vsel-active-high:
> > +    description: |
> > +      If property is present, use the 'VSEL1' register group for buck control.
> > +      Else, use the 'VSEL0' register group. This depends on external hardware
> > +      'VSEL' pin connecton.
> > +    type: boolean
> > +
> > +  regulator-allowed-modes:
> > +    description: |
> > +      buck allowed operating mode
> > +        0: Auto PFM/PWM mode
> > +        1: Forced PWM mode
> > +    maxItems: 2
> > +    items:
> > +      enum: [0, 1]
> 
> So you always require two items? Thus I wonder what's the point of
> having it in DT? To skip the property entirely if none of the modes are
> allowed?
>
Not always need two. So does it mean no need to describe the 'maxItems' and 'Items'.
Keep the description of 'regulator-allowed-modes' to tell the user what the valid value is.
> 
> Best regards,
> Krzysztof
>