linux-kernel - Re: [PATCH] dt-bindings: firmware: Add documentation for qcom,platform-parts-info

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Date:   Mon, 4 Sep 2023 18:04:32 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Naman Jain <quic_namajain@...cinc.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_pkondeti@...cinc.com,
        quic_kaushalk@...cinc.com, quic_rohiagar@...cinc.com,
        kernel@...cinc.com
Subject: Re: [PATCH] dt-bindings: firmware: Add documentation for
 qcom,platform-parts-info

On 4.09.2023 10:38, Naman Jain wrote:
> 
> On 9/1/2023 12:52 PM, Krzysztof Kozlowski wrote:
>> On 01/09/2023 08:02, Naman Jain wrote:
>>> Add documentation to describe device tree bindings for QCOM's
>>> platform-parts-info node. Firmware populates these nodes to pass the
>>> information to kernel regarding the subset of hardware blocks
>>> and features like Camera, Modem, Display present in a product.
>>>
>>> This is to support that the same software image runs seamlessly on
>>> different platforms where one or more HW blocks are not supported or
>>> if some sub parts for a particular block are not supported.
>>>
>>> Purpose of these definitions is to allow clients to know about this,
>>> and thus, handle these cases gracefully.
>> Whether camera is or is not supported, is defined by presence of camera
>> node or by its status field.
>>
>> Existing firmware (e.g. U-Boot) is also doing this - patching DTS when
>> needed.
>>
>> I do not think introducing some parallel way makes any sense, so no,
>> that's not the way to do it.
>>
>> Best regards,
>> Krzysztof
> 
> 
> Thanks Krzysztof for reviewing the patch. I think for telling whether the Camera HW block is not
> supported / not present, firmware can either remove the device tree node, or change its status
> to disabled, so that is fine.
Messing with the device tree for no reason (e.g. filling in
/memory@...ething/reg is expected) or without user intervention
(e.g. static DTBO flashed by the user) is not favored.

Konrad