linux-kernel - Re: [RESEND PATCH v6 1/7] dt-bindings: clock: Add StarFive JH7110 PLL clock generator

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Message-ID: <1b55f255-a9b2-1f0a-9b8b-11c787e76a75@starfivetech.com>
Date:   Fri, 14 Jul 2023 14:24:28 +0800
From:   Xingyu Wu <xingyu.wu@...rfivetech.com>
To:     Emil Renner Berthing <emil.renner.berthing@...onical.com>
CC:     <linux-riscv@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        "Michael Turquette" <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rob Herring" <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Conor Dooley <conor@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        "Hal Feng" <hal.feng@...rfivetech.com>,
        William Qiu <william.qiu@...rfivetech.com>,
        <linux-kernel@...r.kernel.org>, <linux-clk@...r.kernel.org>
Subject: Re: [RESEND PATCH v6 1/7] dt-bindings: clock: Add StarFive JH7110 PLL
 clock generator

On 2023/7/13 20:26, Emil Renner Berthing wrote:
> On Tue, 4 Jul 2023 at 08:49, Xingyu Wu <xingyu.wu@...rfivetech.com> wrote:
>>
>> Add bindings for the PLL clock generator on the JH7110 RISC-V SoC.
>>
>> Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
>> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> Signed-off-by: Xingyu Wu <xingyu.wu@...rfivetech.com>
>> ---
>>  .../bindings/clock/starfive,jh7110-pll.yaml   | 46 +++++++++++++++++++
>>  .../dt-bindings/clock/starfive,jh7110-crg.h   |  6 +++
>>  2 files changed, 52 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/clock/starfive,jh7110-pll.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/clock/starfive,jh7110-pll.yaml b/Documentation/devicetree/bindings/clock/starfive,jh7110-pll.yaml
>> new file mode 100644
>> index 000000000000..beb78add5a8d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/starfive,jh7110-pll.yaml
>> @@ -0,0 +1,46 @@
>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/clock/starfive,jh7110-pll.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: StarFive JH7110 PLL Clock Generator
>> +
>> +description:
>> +  These PLLs are high speed, low jitter frequency synthesizers in JH7110.
> 
> ..synthesizers in the JH7110.

Will fix.

> 
>> +  Each PLL works in integer mode or fraction mode, with configuration
>> +  registers in the sys syscon. So the PLLs node should be a child of
>> +  SYS-SYSCON node.
>> +  The formula for calculating frequency is
>> +  Fvco = Fref * (NI + NF) / M / Q1
>> +
>> +maintainers:
>> +  - Xingyu Wu <xingyu.wu@...rfivetech.com>
>> +
>> +properties:
>> +  compatible:
>> +    const: starfive,jh7110-pll
>> +
>> +  clocks:
>> +    maxItems: 1
>> +    description: Main Oscillator (24 MHz)
>> +
>> +  '#clock-cells':
>> +    const: 1
>> +    description:
>> +      See <dt-bindings/clock/starfive,jh7110-crg.h> for valid indices.
>> +
>> +required:
>> +  - compatible
>> +  - clocks
>> +  - '#clock-cells'
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    clock-controller {
>> +      compatible = "starfive,jh7110-pll";
>> +      clocks = <&osc>;
>> +      #clock-cells = <1>;
>> +    };
>> diff --git a/include/dt-bindings/clock/starfive,jh7110-crg.h b/include/dt-bindings/clock/starfive,jh7110-crg.h
>> index 06257bfd9ac1..086a6ddcf380 100644
>> --- a/include/dt-bindings/clock/starfive,jh7110-crg.h
>> +++ b/include/dt-bindings/clock/starfive,jh7110-crg.h
>> @@ -6,6 +6,12 @@
>>  #ifndef __DT_BINDINGS_CLOCK_STARFIVE_JH7110_CRG_H__
>>  #define __DT_BINDINGS_CLOCK_STARFIVE_JH7110_CRG_H__
>>
>> +/* PLL clocks */
>> +#define JH7110_CLK_PLL0_OUT                    0
>> +#define JH7110_CLK_PLL1_OUT                    1
>> +#define JH7110_CLK_PLL2_OUT                    2
>> +#define JH7110_PLLCLK_END                      3
> 
> It would be nice if these names followed the same pattern as the
> clocks below. Eg. something like JH7110_PLLCLK_PLL?_OUT and
> JH7110_PLLCLK_END.
> 
> But maybe these defines are not even needed, since you just do <&pll
> 0>, <&pll 1> and it's obvious what that means.

I prefer to keep these names because they are used in the PLL driver
and are more easy to understand than numbers.
I will use the JH7110_PLLCLK_PLL?_OUT to follow the same pattern
in next version.

Best regards,
Xingyu Wu

> 
>>  /* SYSCRG clocks */
>>  #define JH7110_SYSCLK_CPU_ROOT                 0
>>  #define JH7110_SYSCLK_CPU_CORE                 1
>> --
>> 2.25.1
>>