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Date:   Mon, 28 Feb 2022 10:20:39 +0100
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Subject: Re: [PATCH v9 05/10] dt-bindings: clock: Add bindings for SP7021
 clock driver
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To:     =?UTF-8?B?cWluamlhblvopoPlgaVd?= <qinjian@cqplus1.com>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>
Cc:     "mturquette@baylibre.com" <mturquette@baylibre.com>,
        "sboyd@kernel.org" <sboyd@kernel.org>,
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        "maz@kernel.org" <maz@kernel.org>,
        "p.zabel@pengutronix.de" <p.zabel@pengutronix.de>,
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        "arnd@arndb.de" <arnd@arndb.de>,
        "stefan.wahren@i2se.com" <stefan.wahren@i2se.com>,
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        <linux-arm-kernel@lists.infradead.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-clk@vger.kernel.org" <linux-clk@vger.kernel.org>,
        =?UTF-8?B?V2VsbHMgTHUg5ZGC6Iqz6aiw?= <wells.lu@sunplus.com>,
        Rob Herring <robh@kernel.org>
References: <cover.1645413746.git.qinjian@cqplus1.com>
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 <498e89dd-c438-68dc-69b5-8de82045ffbd@canonical.com>
 <97cf98c598a04b77bb6de6e91fcdcc0b@cqplus1.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
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On 28/02/2022 07:31, qinjian[覃健] wrote:
>>> +examples:
>>> +  - |
>>> +    clkc: clock-controller@9c000000 {
>>> +      compatible = "sunplus,sp7021-clkc";
>>> +      #clock-cells = <1>;
>>> +      reg = <0x9c000000 0x280>;
>>> +      clocks = <&extclk>, <&clkc PLL_SYS>;
>>
>> Except the warning pointed out by Rob's bot, it looks like you feed this
>> clock-controller with a clock from itself. Is there a point to express
>> it in DTS at all?
>  
> Yes, pllsys is an internal clock, but it also as a parent clock for some other
> clocks in this clock-controller.

What is the point to express it in DTS? Usually such internal
parent-child relation is described in the driver.

And how does it even work? How can you get a clock from a device before
you registered that device?


Best regards,
Krzysztof