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Date:   Tue, 27 Jun 2023 11:11:01 +0200
From:   Marijn Suijten <marijn.suijten@somainline.org>
To:     Krzysztof Kozlowski <krzk@kernel.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Clark <robdclark@gmail.com>,
        Abhinav Kumar <quic_abhinavk@quicinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Sean Paul <sean@poorly.run>, David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Krishna Manikandan <quic_mkrishn@quicinc.com>,
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        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Martin Botka <martin.botka@somainline.org>,
        Jami Kettunen <jami.kettunen@somainline.org>,
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        Lux Aliaga <they@mint.lgbt>
Subject: Re: [PATCH 03/15] dt-bindings: clock: qcom,dispcc-sm6125: Require
 GCC PLL0 DIV clock
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On 2023-06-27 11:07:22, Krzysztof Kozlowski wrote:
> On 27/06/2023 11:02, Marijn Suijten wrote:
> >>>>> So deleting a new item at the end does not matter.  But what if I respin
> >>>>> this patch to add the new clock _at the end_, which will then be at the
> >>>>> same index as the previous GCC_DISP_AHB_CLK?
> >>>>
> >>>> I think you know the answer, right? What do you want to prove? That two
> >>>> independent changes can have together negative effect? We know this.
> >>>
> >>> The question is whether this is allowed?
> >>
> >> That would be an ABI break and I already explained if it is or is not
> >> allowed.
> > 
> > How should we solve it then, if we cannot remove GCC_DISP_AHB_CLK in one
> > patch and add GCC_DISP_GPLL0_DIV_CLK_SRC **at the end** in the next
> > patch?  Keep an empty spot at the original index of GCC_DISP_AHB_CLK?
> 
> I don't know if you are trolling me or really asking question, so just
> in case it is the latter:

Apologies if it comes across that way, but I am genuinely
misunderstanding what is and is not allowed as part of this ABI...

> "No one is locked into the ABI. SoC maintainer decides on this. "

Especially if it is up to the SoC mantainer.

> Also:
> https://lore.kernel.org/linux-arm-msm/20230608152759.GA2721945-robh@kernel.org/
> 
> https://lore.kernel.org/linux-arm-msm/CAL_JsqKOq+PdjUPVYqdC7QcjGxp-KbAG_O9e+zrfY7k-wRr1QQ@mail.gmail.com/
> 
> https://lore.kernel.org/linux-arm-msm/20220602143245.GA2256965-robh@kernel.org/
> 
> https://lore.kernel.org/linux-arm-msm/20220601202452.GA365963-robh@kernel.org/
> 
> Any many more.

In that sense the question above is not for you, but for the SoC
maintainer?  Whom, I hope, will say that we can be lenient in changing
the ABI for a platform that is only slowly being brought up by a bunch
of community developers and unlikely to be touched by anyone else.

Thanks for helping out so far!

- Marijn