Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <1a16cce9fe164bafc06ae193310be71c6f645d75.camel@mediatek.com>
Subject: Re: [PATCH 2/7] dt-bindings: phy: mediatek,tphy: add property to
 set pre-emphasis
From:   Chunfeng Yun <chunfeng.yun@mediatek.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>
CC:     Kishon Vijay Abraham I <kishon@ti.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>,
        <linux-phy@lists.infradead.org>, <devicetree@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        Eddie Hung <eddie.hung@mediatek.com>
Date:   Fri, 26 Aug 2022 13:36:43 +0800
In-Reply-To: <bee8abe5-0299-d05e-643c-4810aa33f978@linaro.org>
References: <20220819091344.2274-1-chunfeng.yun@mediatek.com>
         <20220819091344.2274-2-chunfeng.yun@mediatek.com>
         <438da392-f419-ad76-7e91-aa4aab36e12c@linaro.org>
         <816ecf6287533137b750c8bde9de5830e4229c56.camel@mediatek.com>
         <bee8abe5-0299-d05e-643c-4810aa33f978@linaro.org>
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Tue, 2022-08-23 at 13:24 +0300, Krzysztof Kozlowski wrote:
> On 22/08/2022 10:07, Chunfeng Yun wrote:
> > On Fri, 2022-08-19 at 15:15 +0300, Krzysztof Kozlowski wrote:
> > > On 19/08/2022 12:13, Chunfeng Yun wrote:
> > > > Add a property to set usb2 phy's pre-emphasis.
> > > > 
> > > > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > > > ---
> > > >  Documentation/devicetree/bindings/phy/mediatek,tphy.yaml | 7
> > > > +++++++
> > > >  1 file changed, 7 insertions(+)
> > > > 
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
> > > > b/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
> > > > index 848edfb1f677..aee2f3027371 100644
> > > > --- a/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
> > > > +++ b/Documentation/devicetree/bindings/phy/mediatek,tphy.yaml
> > > > @@ -219,6 +219,13 @@ patternProperties:
> > > >          minimum: 1
> > > >          maximum: 15
> > > >  
> > > > +      mediatek,pre-emphasis:
> > > > +        description:
> > > > +          The selection of pre-emphasis (U2 phy)
> > > > +        $ref: /schemas/types.yaml#/definitions/uint32
> > > > +        minimum: 1
> > > > +        maximum: 3
> > > 
> > > Instead of hard-coding register values in bindings, you should
> > > rather
> > > describe here feature/effect. If it is in units, use unit
> > > suffixes.
> > > If
> > > it is some choice, usually string enum is appropriate.
> > 
> > How about changing description as bellow:
> > 
> > "The level of pre-emphasis, increases one level, boosts the
> > relative
> > amplitudes of signal's higher frequencies components about 4.16%
> > (U2
> > phy)"
> > 
> 
> Still the question is what is the unit. 4.16%?
No unit, it's a level value, like an index of array.

> 
> Best regards,
> Krzysztof