linux-kernel - Re: [PATCH v4 1/2] dt-bindings: arm: qcom: Document the sc7280 CRD Pro boards

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Message-ID: <CAD=FV=WJWnGKgw74nW_VteSwaMswskT7_sQ3iz3YZvsBMfOyxA@mail.gmail.com>
Date:   Thu, 26 Jan 2023 16:20:10 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Rajendra Nayak <quic_rjendra@...cinc.com>
Cc:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        andersson@...nel.org, Matthias Kaehlcke <mka@...omium.org>,
        agross@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, konrad.dybcio@...aro.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] dt-bindings: arm: qcom: Document the sc7280 CRD
 Pro boards

Hi,

On Mon, Jan 9, 2023 at 8:21 PM Rajendra Nayak <quic_rjendra@...cinc.com> wrote:
>
>
> On 1/10/2023 3:12 AM, Doug Anderson wrote:
> > Hi,
> >
> > On Mon, Jan 9, 2023 at 1:36 PM Dmitry Baryshkov
> > <dmitry.baryshkov@...aro.org> wrote:
> >>
> >> On 09/01/2023 23:00, Doug Anderson wrote:
> >>> Hi,
> >>>
> >>> On Tue, Dec 20, 2022 at 9:12 AM Dmitry Baryshkov
> >>> <dmitry.baryshkov@...aro.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@...cinc.com>
> >>>>>>>>> Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >>>>>>>>> Reviewed-by: Matthias Kaehlcke <mka@...omium.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
>
> Thanks Doug for the clarifications, I seem to have missed responding to this
> once I was back from vacation,
>
> >>> 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.
> >>
> >> So, this is a new SoC. Is it 100% compatible with the sc7280? In other
> >> words: does it require any additional customizations (in OPP tables, in
> >> frequences, speed bins, etc)?
>
> Yes, the OPP differences are taken care of with no changes needed in kernel.
> We describe a superset of *all* OPPs supported by a SoC family in DT and the
> cpufreq driver then queries the firmware for supported OPPs on a given
> SoC variant and ends up disabling the rest.

I saw that Bjorn just send out a pull request but it didn't include
this patch. Bjorn: are you expecting anything from Rajendra here, or
did it just get missed? I think Rajendra responded to all of Dmitry's
comments, but I could be mistaken.

-Doug