Re: [PATCH v1 08/25] dt-bindings: clock: mt8173: Add dummy clock ID

From: AngeloGioacchino Del Regno  <angelogioacchino.delregno@collabora.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	mturquette@baylibre.com
Cc: sboyd@kernel.org, matthias.bgg@gmail.com, robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, wenst@chromium.org,
	johnson.wang@mediatek.com, miles.chen@mediatek.com,
	fparent@baylibre.com, chun-jie.chen@mediatek.com,
	sam.shih@mediatek.com, y.oudjana@protonmail.com,
	nfraprado@collabora.com, rex-bc.chen@mediatek.com,
	ryder.lee@kernel.org, daniel@makrotopia.org,
	jose.exposito89@gmail.com, yangyingliang@huawei.com,
	pablo.sun@mediatek.com, msp@baylibre.com, weiyi.lu@mediatek.com,
	ikjn@chromium.org, linux-kernel@vger.kernel.org,
	linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
	kernel@collabora.com
Subject: Re: [PATCH v1 08/25] dt-bindings: clock: mt8173: Add dummy clock ID
Date: Fri, 23 Dec 2022 10:28:53 +0100	[thread overview]
Message-ID: <a9f9a86d-459e-314d-446e-e24b5ee469fe@collabora.com> (raw)
In-Reply-To: <46edd627-c128-b979-823f-0a94fe9d425b@linaro.org>

Il 23/12/22 10:26, Krzysztof Kozlowski ha scritto:
> On 23/12/2022 10:21, AngeloGioacchino Del Regno wrote:
>> Il 23/12/22 09:52, Krzysztof Kozlowski ha scritto:
>>> On 22/12/2022 12:48, AngeloGioacchino Del Regno wrote:
>>>> Some old MediaTek clock drivers are starting the clock count (so, the
>>>> clock ID) from one instead of zero and this is logically incorrect,
>>>> as we should start from 0.
>>>> During a cleanup an issue emerged due to that and the cleanest and
>>>> shortest way to keep devicetree backwards compatibility while still
>>>> performing the well deserved cleanup is to add a dummy clock where
>>>> needed, with ID 0.
>>>
>>> Unfortunately I do not understand at all why adding dummy (fake) ID
>>> cleans anything here. Unifying IDs to start from 0 is not an argument on
>>> DT bindings header IDs.
>>>
>>> Best regards,
>>> Krzysztof
>>>
>>>
>>
>> All clocks are in one or multiple arrays, and if we don't register ID 0,
>> devicetrees will reference the wrong clock, as the IDs will shift back by
>> one during registration.
> 
> So what stops you to register some 0-dummy clock? Why do you need a
> binding for it?
> 
>> This was done for a commonization of probe() and remove() callbacks for
>> MediaTek clock drivers... since we have 3 affected SoCs (MT8173, MT2701
>> and MT6779) out of *19* (soon 20), to me, it didn't make sense to write
>> commonized code to address this just because of 3 out of 20 SoCs (note
>> that each SoC has around 4 clock drivers).
>>
>> Any suggestion to keep this one short, while not touching dt-bindings?
> 
> Just add a clock or better empty entry in your table, without touching
> bindings.
> 

Okay, now that's embarassing - that's a simpler and obvious solution I
should've thought of before sending this series. Heh.

Thanks, by the way!

Regards,
Angelo