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[109.73.99.134]) by smtp.gmail.com with ESMTPSA id y9-20020a196409000000b0048af749c060sm1863927lfb.157.2022.08.30.23.03.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Aug 2022 23:03:46 -0700 (PDT) Message-ID: <3c180570-ecf9-3db4-c698-39c1b4679c6e@linaro.org> Date: Wed, 31 Aug 2022 09:03:45 +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> <0a82842d-283c-e266-84f4-6306f29b61da@linaro.org> <8dcb4de53a52ab44d40f490099b6ed13e5ef7fe0.camel@mediatek.com> From: Krzysztof Kozlowski In-Reply-To: <8dcb4de53a52ab44d40f490099b6ed13e5ef7fe0.camel@mediatek.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220830_230353_014308_B558B67E X-CRM114-Status: GOOD ( 13.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 31/08/2022 06:00, Chunfeng Yun wrote: > On Tue, 2022-08-30 at 13:08 +0300, Krzysztof Kozlowski wrote: >> 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.ya >>>>>>>>> ml | >>>>>>>>> 7 >>>>>>>>> +++++++ >>>>>>>>> 1 file changed, 7 insertions(+) >>>>>>>>> >>>>>>>>> diff --git >>>>>>>>> a/Documentation/devicetree/bindings/phy/mediatek,tphy.y >>>>>>>>> aml >>>>>>>>> b/Documentation/devicetree/bindings/phy/mediatek,tphy.y >>>>>>>>> aml >>>>>>>>> index 848edfb1f677..aee2f3027371 100644 >>>>>>>>> --- >>>>>>>>> a/Documentation/devicetree/bindings/phy/mediatek,tphy.y >>>>>>>>> aml >>>>>>>>> +++ >>>>>>>>> b/Documentation/devicetree/bindings/phy/mediatek,tphy.y >>>>>>>>> aml >>>>>>>>> @@ -219,6 +219,13 @@ patternProperties: >>>>>>>>> minimum: 1 >>>>>>>>> maximum: 15 >>>>>>>>> >>>>>>>>> + mediatek,pre-emphasis: >>>>>>>>> + description: >>>>>>>>> + The selection of pre-emphasis (U2 phy) >>>>>>>>> + $ref: /schemas/types.yaml#/definitions/uint32 >>>>>>>>> + minimum: 1 >>>>>>>>> + maximum: 3 >>>>>>>> >>>>>>>> Instead of hard-coding register values in bindings, you >>>>>>>> should >>>>>>>> rather >>>>>>>> describe here feature/effect. If it is in units, use unit >>>>>>>> suffixes. >>>>>>>> If >>>>>>>> it is some choice, usually string enum is appropriate. >>>>>>> >>>>>>> How about changing description as bellow: >>>>>>> >>>>>>> "The level of pre-emphasis, increases one level, boosts the >>>>>>> relative >>>>>>> amplitudes of signal's higher frequencies components about >>>>>>> 4.16% >>>>>>> (U2 >>>>>>> phy)" >>>>>>> >>>>>> >>>>>> Still the question is what is the unit. 4.16%? >>>>> >>>>> No unit, it's a level value, like an index of array. >>>>> >>>> >>>> So a value from register/device programming? >>> >>> Yes >>>> Rather a regular units >>>> should be used if that's possible. If not, this should be clearly >>>> described here, not some magical number which you encode into >>>> DTS... >>> >>> Ok, I'll add more descriptions. >> >> Better use logical value, e.g. >> > https://urldefense.com/v3/__https://github.com/devicetree-org/dt-schema/blob/main/dtschema/schemas/property-units.yaml*L38__;Iw!!CTRNKA9wMg0ARbw!1e-h0R_uwcaHKfKC9qYfaRWYeuWRq1sLCGy3yupNmkFyuW5s1nmRotL7Y0vFG9ETLLTA$ >> > Optional unit may be -percent or -bp, but the value 4.16% * X > (X=1,2,3...)is not an exact value, they are variable in a range and > dependent more factors. > So I think use level value is simple enough. Then again explain exactly what are the levels. How you wrote it last time, -bp would do the trick. Best regards, Krzysztof _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel