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From:   Doug Anderson <dianders@chromium.org>
Date:   Mon, 9 Jan 2023 13:00:23 -0800
Message-ID: <CAD=FV=X3DyMrEWESV2cWvqg_TQYnj+VGFBQodAp+gfbhBz6X3Q@mail.gmail.com>
Subject: Re: [PATCH v4 1/2] dt-bindings: arm: qcom: Document the sc7280 CRD
 Pro boards
To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        andersson@kernel.org
Cc:     Rajendra Nayak <quic_rjendra@quicinc.com>,
        Matthias Kaehlcke <mka@chromium.org>, agross@kernel.org,
        robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
        konrad.dybcio@linaro.org, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi,

On Tue, Dec 20, 2022 at 9:12 AM Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> wrote:
>
> On 20/12/2022 18:20, Rajendra Nayak wrote:
> >
> >
> > On 12/20/2022 8:00 PM, Matthias Kaehlcke wrote:
> >> On Tue, Dec 20, 2022 at 10:30:32AM +0530, Rajendra Nayak wrote:
> >>>
> >>> On 12/16/2022 7:49 PM, Matthias Kaehlcke wrote:
> >>>> On Fri, Dec 16, 2022 at 04:59:17PM +0530, Rajendra Nayak wrote:
> >>>>> Add compatibles for the Pro SKU of the sc7280 CRD boards
> >>>>> which come with a Pro variant of the qcard.
> >>>>> The Pro qcard variant has smps9 from pm8350c ganged up with
> >>>>> smps7 and smps8.
> >>>>>
> >>>>> Signed-off-by: Rajendra Nayak <quic_rjendra@quicinc.com>
> >>>>> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >>>>> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> >>>>> ---
> >>>>> v4 changes:
> >>>>> Added the zoglin-sku1536 compatible along with hoglin-sku1536.
> >>>>> Zoglin is same as the Hoglin variant, with the SPI Flash reduced
> >>>>> from 64MB to 8MB
> >>>>>
> >>>>>    Documentation/devicetree/bindings/arm/qcom.yaml | 6 ++++++
> >>>>>    1 file changed, 6 insertions(+)
> >>>>>
> >>>>> diff --git a/Documentation/devicetree/bindings/arm/qcom.yaml
> >>>>> b/Documentation/devicetree/bindings/arm/qcom.yaml
> >>>>> index 1b5ac6b02bc5..07771d4c91bd 100644
> >>>>> --- a/Documentation/devicetree/bindings/arm/qcom.yaml
> >>>>> +++ b/Documentation/devicetree/bindings/arm/qcom.yaml
> >>>>> @@ -558,6 +558,12 @@ properties:
> >>>>>              - const: google,hoglin
> >>>>>              - const: qcom,sc7280
> >>>>> +      - description: Qualcomm Technologies, Inc. sc7280 CRD Pro
> >>>>> platform (newest rev)
> >>>>> +        items:
> >>>>> +          - const: google,zoglin-sku1536
> >>>>> +          - const: google,hoglin-sku1536
> >>>>
> >>>> Is there actually such a thing as a 'hoglin-sku1536', i.e. the Pro
> >>>> qcard
> >>>> with 64MB of SPI flash, or do they all have 8MB of flash?
> >>>
> >>> The SPI flash is on the CRD mother-board and not on the qcards, so if
> >>> you replace
> >>> the qcards on the CRDs with 64MB flash you would need the
> >>> hoglin-sku1536 to
> >>> boot on those.
> >>
> >> With such a configuration how does the bootloader know it should pass
> >> the kernel
> >> the device tree for 'hoglin-sku1536' (pro) and not the non-pro
> >> variant? IIUC the
> >> device tree is selected based on pin strappings on the mother-board,
> >> not the
> >> qcard.
> >
> > The device tree is selected based on the pin strappings _and_ additional
> > logic
> > to dynamically identify modem/non-modem(wifi) as well as pro/non-pro
> > SKUs which
> > was added in the bootloaders.
>
> Just to clarify things, when you mention pro SKU, is it a separate SoC
> revision (like sc7280-pro vs bare sc7280), or is it a CRD revision (CRD
> Pro vs bare CRD)?

I guess Rajendra never responded, but since I know the answer: it's a
different SoC revision. ...but the SoC in this case is on a daughter
card, so you could remove the daughter card containing the SoC and put
a new daughtercard on. That would have the effect of making an old CRD
revision have the new Pro SKU SoC.

Bjorn: I'd also note that I think this series (this patch and the next
one) are ready to land.

-Doug