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

[Dmitry Baryshkov]

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@xxxxxxxxxxx>
> > > > > Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> > > > > Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> > > > > ---
> > > > > 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)?

--
With best wishes
Dmitry