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

[Krzysztof Kozlowski]

On 04/11/2022 06:49, Aakarsh Jain wrote:
> 
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski [mailto:krzysztof.kozlowski@xxxxxxxxxx]
>> Sent: 03 November 2022 18:04
>> To: Aakarsh Jain <aakarsh.jain@xxxxxxxxxxx>; linux-arm-
>> kernel@xxxxxxxxxxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx; linux-
>> kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx
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>> 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@xxxxxxxxxxx>
>>> 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@xxxxxxxxxxx>
>>> ---
>>>  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