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([2a02:810d:15c0:828:458e:64e7:8cf1:78b0]) by smtp.gmail.com with ESMTPSA id r5-20020a1709064d0500b00923f05b2931sm4588816eju.118.2023.03.20.09.27.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 20 Mar 2023 09:27:23 -0700 (PDT) Message-ID: Date: Mon, 20 Mar 2023 17:27:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [EXT] Re: [PATCH v2 1/3] dt-bindings: usb: cdns-imx8qm: add imx8qm cdns3 glue bindings To: Frank Li , "shawnguo@kernel.org" Cc: "devicetree@vger.kernel.org" , "festevam@gmail.com" , "imx@lists.linux.dev" , "kernel@pengutronix.de" , "krzysztof.kozlowski+dt@linaro.org" , "linux-arm-kernel@lists.infradead.org" , dl-linux-imx , "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , "s.hauer@pengutronix.de" References: <20230316212712.2426542-1-Frank.Li@nxp.com> <20230316212712.2426542-2-Frank.Li@nxp.com> <1fd1fe42-3da6-1598-a04d-cb99a9b4b145@linaro.org> Content-Language: en-US From: Krzysztof Kozlowski In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20/03/2023 17:22, Frank Li wrote: >>>>>>> + assigned-clocks: >>>>>>> + items: >>>>>>> + - description: Phandle and clock specifier of >> IMX_SC_PM_CLK_PER. >>>>>>> + - description: Phandle and clock specifoer of >>>> IMX_SC_PM_CLK_MISC. >>>>>>> + - description: Phandle and clock specifoer of >>>>>> IMX_SC_PM_CLK_MST_BUS. >>>>>>> + >>>>>>> + assigned-clock-rates: >>>>>>> + items: >>>>>>> + - description: Must be 125 Mhz. >>>>>>> + - description: Must be 12 Mhz. >>>>>>> + - description: Must be 250 Mhz. >>>>>> >>>>>> I would argue that both properties above are not needed. If your >>>>>> hardware requires fixed frequencies, clock provider can fix them, can't >> it? >>>>> >>>>> Clock provider don't know fixed value and turn on only used by client. >>>> >>>> So maybe fix the clock provider? Or this device driver? Requiring by >>>> binding specific frequencies for every board is a bit redundant. >>> >>> It is not for every boards, it is common for a chip family. Only a place to set >> for >>> QM and QXP. >>> >>> The similar case is network driver, which require a specific frequency at >> clock assign. >>> Generally frequency is fixed, clock source name may change at difference >> chips. >> >> If frequency is always fixed, I don't understand why this is in DT >> bindings. I would even say it should not be in DTS. We don't put into >> DTS properties which are always the same, because otherwise they would >> grow crazy big. > > Although frequency is fixed, clock name may change for difference platform. > > assigned-clocks = <&clk IMX_SC_R_USB_2 IMX_SC_PM_CLK_PER>, > <&clk IMX_SC_R_USB_2 IMX_SC_PM_CLK_MISC>, > <&clk IMX_SC_R_USB_2 IMX_SC_PM_CLK_MST_BUS>; > assigned-clock-rates = <125000000>, <12000000>, <250000000>; > > some platform use IMX_SC_R_USB_2, other platform may use IMX_SC_R_USB_3. This I understand, you wrote it above, so nothing new and my concerns are still there. Best regards, Krzysztof