linux-kernel - Re: [PATCH V6 1/3] dt-bindings: sram: qcom,imem: Add Boot Stat region within IMEM

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Message-ID: <CAA8EJprJfmtFs1dx0uJw0bi1ig2JsCYzH_4BncPop4aO16D2aA@mail.gmail.com>
Date:   Tue, 9 May 2023 16:05:53 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Souradeep Chowdhury <quic_schowdhu@...cinc.com>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        Sibi Sankar <quic_sibis@...cinc.com>,
        Rajendra Nayak <quic_rjendra@...cinc.com>
Subject: Re: [PATCH V6 1/3] dt-bindings: sram: qcom,imem: Add Boot Stat region
 within IMEM

On Tue, 9 May 2023 at 15:21, Souradeep Chowdhury
<quic_schowdhu@...cinc.com> wrote:
>
>
>
> On 5/9/2023 5:05 PM, Dmitry Baryshkov wrote:
> > On Tue, 9 May 2023 at 13:53, Souradeep Chowdhury
> > <quic_schowdhu@...cinc.com> wrote:
> >>
> >> All Qualcomm bootloaders log useful timestamp information related
> >> to bootloader stats in the IMEM region. Add the child node within
> >> IMEM for the boot stat region containing register address and
> >> compatible string.
> >
> > I might have a minor vote here. Is there any reason why you have to
> > instantiate the device from DT?
> > It looks like a software interface. Ideally software should not be
> > described in DT (e.g. this can be instantiated from imem
> > driver-to-be).
> > Or we can follow the RPM master-stats approach, where the device is a
> > top-level device, having handle pointers to the sram regions.
>
> This is a dedicated region of IMEM reserved for storing stats related
> information. So it is represented as a child of IMEM, please
> refer to Documentation/devicetree/bindings/sram/sram.yaml which
> follows a similar philosophy. Also since this is a child of IMEM with
> a specific purpose, does it not warrant a dedicated driver?

I do not question a dedicated driver. I was asking about the DT node.
Even the mentioned bindings file describes the SRAM regions inside the
SRAM, rather than a proper device to be instantiated in the SRAM node.
I'd point to the boot_stats discussions (present on the list in the
last several months).

>
> >
> >>
> >> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@...cinc.com>
> >> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >> ---
> >>   .../devicetree/bindings/sram/qcom,imem.yaml   | 22 +++++++++++++++++++
> >>   1 file changed, 22 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/sram/qcom,imem.yaml b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
> >> index 0548e8e0d30b..bb884c5c8952 100644
> >> --- a/Documentation/devicetree/bindings/sram/qcom,imem.yaml
> >> +++ b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
> >> @@ -50,6 +50,28 @@ patternProperties:
> >>       $ref: /schemas/remoteproc/qcom,pil-info.yaml#
> >>       description: Peripheral image loader relocation region
> >>
> >> +  "^stats@[0-9a-f]+$":
> >> +    type: object
> >> +    description:
> >> +      Imem region dedicated for storing timestamps related
> >> +      information regarding bootstats.
> >> +
> >> +    additionalProperties: false
> >> +
> >> +    properties:
> >> +      compatible:
> >> +        items:
> >> +          - enum:
> >> +              - qcom,sm8450-bootstats
> >> +          - const: qcom,imem-bootstats
> >> +
> >> +      reg:
> >> +        maxItems: 1
> >> +
> >> +    required:
> >> +      - compatible
> >> +      - reg
> >> +
> >>   required:
> >>     - compatible
> >>     - reg
> >> --
> >> 2.17.1
> >>
> >
> >



-- 
With best wishes
Dmitry