linux-kernel - Re: [PATCH 6/6] riscv: dts: microchip: add the mpfs' fabric clock control

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Date:   Fri, 19 Aug 2022 15:47:48 +0300
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Conor Dooley <conor.dooley@...rochip.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Daire McNamara <daire.mcnamara@...rochip.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 6/6] riscv: dts: microchip: add the mpfs' fabric clock
 control

On 19/08/2022 15:23, Conor Dooley wrote:
> The "fabric clocks" in current PolarFire SoC device trees are not
> really fixed clocks. Their frequency is set by the bitstream, so having
> them located in -fabric.dtsi is not a problem - they're just as "fixed"
> as the IP blocks etc used in the FPGA fabric.
> However, their configuration can be read at runtime (and to an extent
> they can be controlled, although the intended usage is static
> configurations set by the bitstream) through the system controller bus.
> 

Thank you for your patch. There is something to discuss/improve.

> +&pcie {
> +	clocks = <&fabric_clk1>, <&fabric_clk1>, <&fabric_clk3>;
> +	clock-names = "fic0", "fic1", "fic3";
> +};
> diff --git a/arch/riscv/boot/dts/microchip/mpfs.dtsi b/arch/riscv/boot/dts/microchip/mpfs.dtsi
> index 499c2e63ad35..dd15b6d1a3c9 100644
> --- a/arch/riscv/boot/dts/microchip/mpfs.dtsi
> +++ b/arch/riscv/boot/dts/microchip/mpfs.dtsi
> @@ -236,6 +236,38 @@ clkcfg: clkcfg@...02000 {
>  			#clock-cells = <1>;
>  		};
>  
> +		ccc_se: cccseclk@...10000 {

Although you call it "Clock Conditioning Circuitry", but the role of
this device is a clock-controller, isn't it? If so, node names should be
generic, so "clock-controller".

https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation


Best regards,
Krzysztof