Re: [PATCH 3/3] arm64: dts: exynos: Rename compatible string property from version to SOC specific

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 04/11/2022 06:49, Aakarsh Jain wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski [mailto:krzysztof.kozlowski@linaro.org]
>> Sent: 03 November 2022 18:04
>> To: Aakarsh Jain <aakarsh.jain@samsung.com>; linux-arm-
>> kernel@lists.infradead.org; linux-media@vger.kernel.org; linux-
>> kernel@vger.kernel.org; devicetree@vger.kernel.org
>> Cc: m.szyprowski@samsung.com; andrzej.hajda@intel.com;
>> mchehab@kernel.org; hverkuil-cisco@xs4all.nl;
>> ezequiel@vanguardiasur.com.ar; jernej.skrabec@gmail.com;
>> benjamin.gaignard@collabora.com; krzysztof.kozlowski+dt@linaro.org;
>> stanimir.varbanov@linaro.org; dillon.minfei@gmail.com;
>> david.plowman@raspberrypi.com; mark.rutland@arm.com;
>> robh+dt@kernel.org; krzk+dt@kernel.org; andi@etezian.org;
>> alim.akhtar@samsung.com; aswani.reddy@samsung.com;
>> pankaj.dubey@samsung.com; smitha.t@samsung.com
>> Subject: Re: [PATCH 3/3] arm64: dts: exynos: Rename compatible string
>> property from version to SOC specific
>>
>> On 02/11/2022 09:06, Aakarsh Jain wrote:
>>> commit "752d3a23d1f68de87e3c" which adds MFC codec device node for
>>> exynos3250 SOC. Since exynos3250.dtsi and exynos5420.dtsi are using
>>> same compatible string as "samsung,mfc-v7" but their node properties
>>> are different.As both SoCs have MFC v7 hardware module but with
>>> different clock hierarchy and complexity.
>>> So renaming compatible string from version specific to SOC based.
>>>
>>> Suggested-by: Alim Akhtar <alim.akhtar@samsung.com>
>>> Fixes: 752d3a23d1f6 ("ARM: dts: add MFC codec device node for
>>> exynos3250")
>>
>> There is no bug to fix and backporting is forbidden as it breaks the usage of
>> DTS in older kernel.
>>
> Okay will remove this Fix tag in next series.
>>> Signed-off-by: Aakarsh Jain <aakarsh.jain@samsung.com>
>>> ---
>>>  arch/arm/boot/dts/exynos3250.dtsi | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boot/dts/exynos3250.dtsi
>>> b/arch/arm/boot/dts/exynos3250.dtsi
>>> index 326b9e0ed8d3..98105c64f7d9 100644
>>> --- a/arch/arm/boot/dts/exynos3250.dtsi
>>> +++ b/arch/arm/boot/dts/exynos3250.dtsi
>>> @@ -485,7 +485,7 @@
>>>  		};
>>>
>>>  		mfc: codec@13400000 {
>>> -			compatible = "samsung,mfc-v7";
>>> +			compatible = "samsung,exynos3250-mfc";
>>
>> The change is non-bisectable and breaks using DTS in older kernel.
>>
> Right, so what is your suggestion on this?
> I can see two ways here:
> 1> To squash patch2 and patch3 in one?
> 2> Have a warning about this breakage in the patch-3 commit message?

Here - nothing except implementing bindings. The suggestion was given to
the bindings patch - use fallback.

Best regards,
Krzysztof