linux-kernel - Re: [PATCH v3 1/4] dt-bindings: arm: qcom-soc: simplify SoC-matching patterns

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Message-ID: <144458a6-6c63-4386-99da-3a27743288b4@kernel.org>
Date: Fri, 1 Nov 2024 10:23:47 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Krishna Kurapati <quic_kriskura@...cinc.com>,
 linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/4] dt-bindings: arm: qcom-soc: simplify SoC-matching
 patterns

On 01/11/2024 09:52, Dmitry Baryshkov wrote:
> On Fri, Nov 01, 2024 at 09:37:23AM +0100, Krzysztof Kozlowski wrote:
>> On 01/11/2024 08:47, Dmitry Baryshkov wrote:
>>> On Fri, Nov 01, 2024 at 08:26:04AM +0100, Krzysztof Kozlowski wrote:
>>>> On Fri, Nov 01, 2024 at 02:49:22AM +0200, Dmitry Baryshkov wrote:
>>>>> The patterns for individual SoC families grew up to be pretty complex,
>>>>> containing lots of special cases and optional suffixes. Split them per
>>>>> the suffix to make it easier to extend SoC patterns.
>>>>
>>>> This is doing something quite different - split is not important here.
>>>> Instead you narrow the patterns significantly and disallow things like
>>>> msm8994pro, sc8280p or sc8280px, and allow things like sa5200p.
>>>
>>> Just for the sake of correctness, msm8994pro is still allowed, if I'm
>>> not mistaken.
>>>
>>>> I don't see here much of pattern simplifying - dropping (pro)? really
>>>> makes little difference.
>>>
>>> Patterns are simplified by being explicit. E.g. in the previous
>>> iteration I completely didn't notice the intersection of the |p that I
>>> have added with the existing [a-z][a-z]? pattern. If you think that
>>> sa5200p should be disallowed, I can tune the numeric part of the
>>> pattern. And sc8280p / sc8280px should not be allowed in the first
>>> place, such platforms don't exist.
>>
>> I am fine with this, but extend the commit msg with some good rationale.
>> Have in mind that the point of this pattern was *not* to validate SoCs
>> names. sa5200p is fine, sc8180p is fine and all others are fine, sc8280z
>> as well, because we do not want to grow this pattern with every new model.
>>
>> The only, single point of this entire binding is to disallow incorrect
>> order of block names in compatible. Not validate the SoC names. If you
>> need narrower patterns to achieve that objective, sure. If you need
>> narrower patterns to validate SoC names, then nope.
> 
> I need narrower patterns to simplify adding new SoCs.
> Another option is to define a mega-pattern like
> qcom,(msm|sm|sd[am]|.....)[0-9]+[a-z]*-.* . Frankly speaking I'm fine
> with that approach too.

I do not see how narrower patterns, changing:
"^qcom,(sa|sc)8[0-9]+[a-z][a-z]?-.*$"
into
pattern: "^qcom,sa[0-9]+p-.*$"

instead of
pattern: "^qcom,sa[0-9]+[a-z]-.*$"
is needed for that. It's true that 'p' is simpler than '[a-z]' but if
this results in new commit next time we have sa8995r, then benefit is lost.

Best regards,
Krzysztof