linux-kernel - Re: [PATCH V5 1/4] clk: meson: S4: add support for Amlogic S4 SoC PLL clock driver and bindings

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Date:   Mon, 28 Nov 2022 15:39:00 +0800
From:   Yu Tu <yu.tu@...ogic.com>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        <neil.armstrong@...aro.org>, <linux-clk@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-amlogic@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Kevin Hilman <khilman@...libre.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
CC:     <kelvin.zhang@...ogic.com>
Subject: Re: [PATCH V5 1/4] clk: meson: S4: add support for Amlogic S4 SoC PLL
 clock driver and bindings

Hi Jerome,
	Thank you for your reply.

On 2022/11/25 17:23, Jerome Brunet wrote:
> [ EXTERNAL EMAIL ]
> 
> 
> On Wed 23 Nov 2022 at 14:53, Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:
> 
>> On 23/11/2022 14:23, Neil Armstrong wrote:
>>> Hi,
>>>
>>> On 23/11/2022 12:16, Yu Tu wrote:
>>>> Hi Krzysztof,
>>>>       Thank you for your reply.
>>>>
>>>> On 2022/11/23 18:08, Krzysztof Kozlowski wrote:
>>>>> [ EXTERNAL EMAIL ]
>>>>>
>>>>> On 23/11/2022 03:13, Yu Tu wrote:
>>>>>> Add the S4 PLL clock controller found and bindings in the s4 SoC family.
>>>>>>
>>>>>> Signed-off-by: Yu Tu <yu.tu@...ogic.com>
>>>>>> ---
>>>>>>    .../bindings/clock/amlogic,s4-pll-clkc.yaml   |  51 +
>>>>>
>>>>> This is v5 and still bindings are here? Bindings are always separate
>>>>> patches. Use subject prefixes matching the subsystem (git log --oneline
>>>>> -- ...).
>>>>>
>>>>> And this was split, wasn't it? What happened here?!?
>>>>
>>>> Put bindings and clock driver patch together from Jerome. Maybe you can read this chat history.
>>>> https://lore.kernel.or/all/1jy1v6z14n.fsf@starbuckisacylon.baylibre.com/
>>>
>>> Jerome was asking you to send 2 patchsets, one with :
>>> - bindings in separate patches
>>> - drivers in separate patches
>>> and a second with DT changes.
> 
> Indeed, this is what was asked. It is aligned with Krzysztof's request.

According to your discussion, I still should send patches in the 
previous way in series. But I'm going to change it like you suggested.
I don't know, am I getting it right?

> 
>>>
>>> Then when the bindings + clocks patches are merged, a pull request of the bindings
>>> can be done to me so I can merge it with DT.
>>>
>>>>
>>>>>
>>>>>
>>>>>>    MAINTAINERS                                   |   1 +
>>>>>>    drivers/clk/meson/Kconfig                     |  13 +
>>>>>>    drivers/clk/meson/Makefile                    |   1 +
>>>>>>    drivers/clk/meson/s4-pll.c                    | 875 ++++++++++++++++++
>>>>>>    drivers/clk/meson/s4-pll.h                    |  88 ++
>>>>>>    .../dt-bindings/clock/amlogic,s4-pll-clkc.h   |  30 +
>>>>>>    7 files changed, 1059 insertions(+)
>>>>>>    create mode 100644 Documentation/devicetree/bindings/clock/amlogic,s4-pll-clkc.yaml
>>>>>>    create mode 100644 drivers/clk/meson/s4-pll.c
>>>>>>    create mode 100644 drivers/clk/meson/s4-pll.h
>>>>>>    create mode 100644 include/dt-bindings/clock/amlogic,s4-pll-clkc.h
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/clock/amlogic,s4-pll-clkc.yaml b/Documentation/devicetree/bindings/clock/amlogic,s4-pll-clkc.yaml
>>>>>> new file mode 100644
>>>>>> index 000000000000..fd517e8ef14f
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/devicetree/bindings/clock/amlogic,s4-pll-clkc.yaml
>>>>>> @@ -0,0 +1,51 @@
>>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>>> +%YAML 1.2
>>>>>> +---
>>>>>> +$id: http://devicetree.org/schemas/clock/amlogic,s4-pll-clkc.yaml#
>>>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>>>> +
>>>>>> +title: Amlogic Meson S serials PLL Clock Controller
>>>>>> +
>>>>>> +maintainers:
>>>>>> +  - Neil Armstrong <narmstrong@...libre.com>
>>>>>> +  - Jerome Brunet <jbrunet@...libre.com>
>>>>>> +  - Yu Tu <yu.hu@...ogic.com>
>>>>>> +
>>>>> One blank line.
>>>>
>>>>    I will delete this, on next version patch.
>>>>
>>>>>
>>>>>> +
>>>>>> +properties:
>>>>>> +  compatible:
>>>>>> +    const: amlogic,s4-pll-clkc
>>>>>> +
>>>>>> +  reg:
>>>>>> +    maxItems: 1
>>>>>> +
>>>>>> +  clocks:
>>>>>> +    maxItems: 1
>>>>>> +
>>>>>> +  clock-names:
>>>>>> +    items:
>>>>>> +      - const: xtal
>>>>>> +
>>>>>> +  "#clock-cells":
>>>>>> +    const: 1
>>>>>> +
>>>>>> +required:
>>>>>> +  - compatible
>>>>>> +  - reg
>>>>>> +  - clocks
>>>>>> +  - clock-names
>>>>>> +  - "#clock-cells"
>>>>>> +
>>>>>> +additionalProperties: false
>>>>>> +
>>>>>> +examples:
>>>>>> +  - |
>>>>>> +    clkc_pll: clock-controller@...08000 {
>>>>>> +      compatible = "amlogic,s4-pll-clkc";
>>>>>> +      reg = <0xfe008000 0x1e8>;
>>>>>> +      clocks = <&xtal>;
>>>>>> +      clock-names = "xtal";
>>>>>> +      #clock-cells = <1>;
>>>>>> +    };
>>>>>
>>>>>
>>>>>> +#endif /* __MESON_S4_PLL_H__ */
>>>>>> diff --git a/include/dt-bindings/clock/amlogic,s4-pll-clkc.h b/include/dt-bindings/clock/amlogic,s4-pll-clkc.h
>>>>>> new file mode 100644
>>>>>> index 000000000000..345f87023886
>>>>>> --- /dev/null
>>>>>> +++ b/include/dt-bindings/clock/amlogic,s4-pll-clkc.h
>>>>>
>>>>> This belongs to bindings patch, not driver.
>>>>>
>>>>>> @@ -0,0 +1,30 @@
>>>>>> +/* SPDX-License-Identifier: (GPL-2.0+ OR MIT) */
>>>>>> +/*
>>>>>> + * Copyright (c) 2021 Amlogic, Inc. All rights reserved.
>>>>>> + * Author: Yu Tu <yu.tu@...ogic.com>
>>>>>> + */
>>>>>> +
>>>>>> +#ifndef _DT_BINDINGS_CLOCK_AMLOGIC_S4_PLL_CLKC_H
>>>>>> +#define _DT_BINDINGS_CLOCK_AMLOGIC_S4_PLL_CLKC_H
>>>>>> +
>>>>>> +/*
>>>>>> + * CLKID index values
>>>>>> + */
>>>>>> +
>>>>>> +#define CLKID_FIXED_PLL            1
>>>>>> +#define CLKID_FCLK_DIV2            3
>>>>>
>>>>> Indexes start from 0 and are incremented by 1. Not by 2.
>>>>>
>>>>> NAK.
>>>>
>>>> I remember Jerome discussing this with you.You can look at this submission history.
>>>> https://lore.kernel.org/all/c088e01c-0714-82be-8347-6140daf56640@linaro.org/
>>>
>>> Historically we did that by only exposing part of the numbers, controlling which
>>> clocks were part of the bindings.
>>>
>>> But it seems this doesn't make sens anymore, maybe it would be time to put all the
>>> clock ids in the bindings for this new SoC and break with the previous strategy.
> 
> Krzysztof and I agreed there is nothing wrong with the current
> approach, I believe.
> 
> It does not prevent someone from using an un-exposed clock, sure, or
> exposing it in the future if necessary.
> 
> However, I think it clearly shows that an un-exposed element is not
> expected to be used by an external consumers. It should be enough to
> trigger a discussion if this expectation is wrong.
> 
>>
>> So the outcome of the previous discussion was somewhere later in that
>> thread:
>>
>>> It is just a choice to not expose some IDs.
>>> It is not tied to the implementation at all.
>>> I think we actually follow the rules and the idea behind it.
>>
>>
>> Best regards,
>> Krzysztof
> 
> .