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Subject: Re: [PATCH] arm64: dts: qcom: sm8450: delete incorrect ufs
 interconnect fields
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        Vinod Koul <vkoul@kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        linux-arm-msm@vger.kernel.org
References: <20220407172145.31903-1-jonathan@marek.ca>
 <e41c26c2-8aa4-cfd2-27b0-eb011f45eda0@linaro.org>
 <865ff6bc-95a2-8b39-5cf2-bb2d3f592c5a@linaro.org>
From:   Jonathan Marek <jonathan@marek.ca>
Message-ID: <f1fb2d71-4adf-bcc7-76b3-c7102ab9f2e9@marek.ca>
Date:   Thu, 7 Apr 2022 18:38:34 -0400
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On 4/7/22 5:16 PM, Krzysztof Kozlowski wrote:
> On 07/04/2022 21:40, Vladimir Zapolskiy wrote:
>> On 4/7/22 20:21, Jonathan Marek wrote:
>>> Upstream sm8450.dtsi has #interconnect-cells = <2>; so these are wrong.
>>> Ignored and undocumented with upstream UFS driver so delete for now.
> 
> This is the upstream and they are documented here, although as pointed
> by Vladimir this was rather a reverse-documentation. The documentation
> might be incorrect, but then the bindings should be corrected instead of
> only modifying the DTS.
> 
>>
>> Basically the description was added by a commit 462c5c0aa798 ("dt-bindings: ufs:
>> qcom,ufs: convert to dtschema").
>>
>> It's questionable, if an example in the new yaml file is totally correct
>> in connection to the discussed issue.
> 
> To be honest - the example probably is not correct, because it was based
> on existing DTS without your patch. :)
> 
> Another question is whether the interconnect properties are here correct
> at all. I assumed that DTS is correct because it should describe the
> hardware, even if driver does not use it. However maybe that was a false
> assumption...
> 

writing-bindings.rst says it is OK to document even if it isn't used by 
the driver (seems wrong to me, at least for interconnects which are a 
firmware abstraction and not hardware).

462c5c0aa798 wasn't in my 5.17+ tree pulled after dts changes were 
merged (I guess doc changes come later), so my commit message is 
incorrect, but I think it makes more sense to have the documentation 
reflect the driver. Its also not an important issue, so I'll let others 
sort it out.

> 
> Best regards,
> Krzysztof
>