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Date:   Tue, 27 Jun 2023 10:21:12 +0200
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Subject: Re: [PATCH 03/15] dt-bindings: clock: qcom,dispcc-sm6125: Require GCC
 PLL0 DIV clock
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To:     Marijn Suijten <marijn.suijten@somainline.org>
Cc:     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>,
        ~postmarketos/upstreaming@lists.sr.ht,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Martin Botka <martin.botka@somainline.org>,
        Jami Kettunen <jami.kettunen@somainline.org>,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Krzysztof Kozlowski <krzk@kernel.org>,
        linux-clk@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org, Lux Aliaga <they@mint.lgbt>
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From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <3nnk4xvmpnum2q6g6c6crjlqq3ra7j2z5zis53xcqbvevymuhz@mkffvs45n6ut>
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On 27/06/2023 09:49, Marijn Suijten wrote:
> On 2023-06-27 09:29:53, Krzysztof Kozlowski wrote:
>> On 27/06/2023 08:54, Marijn Suijten wrote:
>>> On 2023-06-27 08:24:41, Krzysztof Kozlowski wrote:
>>>> On 26/06/2023 20:53, Marijn Suijten wrote:
>>>>> On 2023-06-26 20:51:38, Marijn Suijten wrote:
>>>>> <snip>
>>>>>>> Not really, binding also defines the list of clocks - their order and
>>>>>>> specific entries. This changes.
>>>>>>
>>>>>> And so it does in "dt-bindings: clock: qcom,dispcc-sm6125: Remove unused
>>>>>> GCC_DISP_AHB_CLK"?
>>>>>
>>>>> Never mind: it is the last item so the order of the other items doesn't
>>>>> change.  The total number of items decreases though, which sounds like
>>>>> an ABI-break too?
>>>>
>>>> How does it break? Old DTS works exactly the same, doesn't it?
>>>
>>> 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.

Best regards,
Krzysztof