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[109.73.99.134]) by smtp.gmail.com with ESMTPSA id z24-20020a2eb538000000b00261b58cbf03sm947843ljm.87.2022.08.30.03.08.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Aug 2022 03:08:42 -0700 (PDT) Message-ID: <0a82842d-283c-e266-84f4-6306f29b61da@linaro.org> Date: Tue, 30 Aug 2022 13:08:40 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [PATCH 2/7] dt-bindings: phy: mediatek,tphy: add property to set pre-emphasis Content-Language: en-US To: Chunfeng Yun , Vinod Koul , Rob Herring Cc: Kishon Vijay Abraham I , Krzysztof Kozlowski , Matthias Brugger , 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 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> <1a16cce9fe164bafc06ae193310be71c6f645d75.camel@mediatek.com> <000babd8-5980-3d77-f156-324b3442cbe7@linaro.org> <114c357f8d7f049d21ede789a292a8e2d45f4c61.camel@mediatek.com> From: Krzysztof Kozlowski In-Reply-To: <114c357f8d7f049d21ede789a292a8e2d45f4c61.camel@mediatek.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 29/08/2022 05:37, Chunfeng Yun wrote: > On Fri, 2022-08-26 at 09:36 +0300, Krzysztof Kozlowski wrote: >> On 26/08/2022 08:36, Chunfeng Yun wrote: >>> 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 >>>>>>> --- >>>>>>> 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. >>> >> >> So a value from register/device programming? > Yes >> Rather a regular units >> should be used if that's possible. If not, this should be clearly >> described here, not some magical number which you encode into DTS... > Ok, I'll add more descriptions. Better use logical value, e.g. https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml#L38 Best regards, Krzysztof