Re: [PATCH 1/7] dt-bindings: PCI: qcom: Add IPQ9574 specific compatible

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On Tue, 7 Mar 2023 at 11:45, Devi Priya <quic_devipriy@quicinc.com> wrote:
>
>
>
> On 3/3/2023 11:10 PM, Manivannan Sadhasivam wrote:
> > On Fri, Mar 03, 2023 at 05:16:58PM +0200, Dmitry Baryshkov wrote:
> >> 28 февраля 2023 г. 08:33:58 GMT+02:00, Manivannan Sadhasivam <mani@kernel.org> пишет:
> >>> On Tue, Feb 28, 2023 at 10:56:53AM +0530, Devi Priya wrote:
> >>>>
> >>>>
> >>>> On 2/24/2023 1:53 PM, Manivannan Sadhasivam wrote:
> >>>>> On Tue, Feb 14, 2023 at 10:11:29PM +0530, Devi Priya wrote:
> >>>>>> Document the compatible for IPQ9574
> >>>>>>
> >>>> Hi Mani, Thanks for taking time to review the patch.
> >>>>>
> >>>>> You didn't mention about the "msi-parent" property that is being added
> >>>>> by this patch
> >>>> Sure, will update the commit message in the next spin
> >>>>>
> >>>>>> Signed-off-by: Devi Priya <quic_devipriy@quicinc.com>
> >>>>>> ---
> >>>>>>    .../devicetree/bindings/pci/qcom,pcie.yaml    | 72 ++++++++++++++++++-
> >>>>>>    1 file changed, 70 insertions(+), 2 deletions(-)
> >>>>>>
> >>>>>> diff --git a/Documentation/devicetree/bindings/pci/qcom,pcie.yaml b/Documentation/devicetree/bindings/pci/qcom,pcie.yaml
> >>>>>> index 872817d6d2bd..dabdf2684e2d 100644
> >>>>>> --- a/Documentation/devicetree/bindings/pci/qcom,pcie.yaml
> >>>>>> +++ b/Documentation/devicetree/bindings/pci/qcom,pcie.yaml
> >>>>>> @@ -26,6 +26,7 @@ properties:
> >>>>>>              - qcom,pcie-ipq8064-v2
> >>>>>>              - qcom,pcie-ipq8074
> >>>>>>              - qcom,pcie-ipq8074-gen3
> >>>>>> +          - qcom,pcie-ipq9574
> >>>>>>              - qcom,pcie-msm8996
> >>>>>>              - qcom,pcie-qcs404
> >>>>>>              - qcom,pcie-sa8540p
> >>>>>> @@ -44,11 +45,11 @@ properties:
> >>>>>>      reg:
> >>>>>>        minItems: 4
> >>>>>> -    maxItems: 5
> >>>>>> +    maxItems: 6
> >>>>>>      reg-names:
> >>>>>>        minItems: 4
> >>>>>> -    maxItems: 5
> >>>>>> +    maxItems: 6
> >>>>>>      interrupts:
> >>>>>>        minItems: 1
> >>>>>> @@ -105,6 +106,8 @@ properties:
> >>>>>>        items:
> >>>>>>          - const: pciephy
> >>>>>> +  msi-parent: true
> >>>>>> +
> >>>>>>      power-domains:
> >>>>>>        maxItems: 1
> >>>>>> @@ -173,6 +176,27 @@ allOf:
> >>>>>>                - const: parf # Qualcomm specific registers
> >>>>>>                - const: config # PCIe configuration space
> >>>>>> +  - if:
> >>>>>> +      properties:
> >>>>>> +        compatible:
> >>>>>> +          contains:
> >>>>>> +            enum:
> >>>>>> +              - qcom,pcie-ipq9574
> >>>>>> +    then:
> >>>>>> +      properties:
> >>>>>> +        reg:
> >>>>>> +          minItems: 5
> >>>>>> +          maxItems: 6
> >>>>>> +        reg-names:
> >>>>>> +          minItems: 5
> >>>>>> +          items:
> >>>>>> +            - const: dbi # DesignWare PCIe registers
> >>>>>> +            - const: elbi # External local bus interface registers
> >>>>>> +            - const: atu # ATU address space
> >>>>>> +            - const: parf # Qualcomm specific registers
> >>>>>> +            - const: config # PCIe configuration space
> >>>>>> +            - const: aggr_noc #PCIe aggr_noc
> >>>>>
> >>>>> Why do you need this region unlike other SoCs? Is the driver making use of it?
> >>>> We have the aggr_noc region in ipq9574 to achieve higher throughput & to
> >>>> handle multiple PCIe instances. The driver uses it to rate adapt 1-lane PCIe
> >>>> clocks. My bad, missed it. Will add the driver changes in V2.
> >>>
> >>> Hmm, this is something new. How can you achieve higher throughput with this
> >>> region? Can you explain more on how it is used?
> >>
> >> Based on the name of the region, it looks like it is an interconnect region.
> >>
> >
> > Well, we only have BCM based interconnects so far. That's why I was curious
> > about this region and its purpose.
> For connected PCIe slave devices that are running at frequency lesser
> than the ANOC frequency (342MHz), the rate adapter of ANOC needs to be
> configured
> >
> >> Devi, if this is the case, then you have to handle it through the interconnect driver, rather than poking directly into these registers.
> >
> > If that so, it doesn't need to be added in this series itself. I believe that
> > without aggr_noc region, the PCIe controller can still function properly with
> > reduced performance. But you can add the interconnect support later as a
> > separate series.
> Sure, okay. The ANOC runs at a fixed frequency of 342MHz and the
> interconnect clocks are not scaled. The aggr_noc register is just a
> magic register for configuring it's rate adapter to ensure no wait
> cycles are inserted.

I have been hesitant at some point, but this looks more and more like
a special kind of interconnect. Please consider moving all the NoC
stuff into a separate driver implementing the ICC API.

>
> >
> > Thanks,
> > Mani
> >
> >>
> >>
> >>>
> >>> Thanks,
> >>> Mani
> >>>
> >>>>>
> >>>>> Thanks,
> >>>>> Mani
> >>>>>
> >>>>>> +
> >>>>>>      - if:
> >>>>>>          properties:
> >>>>>>            compatible:
> >>>>>> @@ -365,6 +389,39 @@ allOf:
> >>>>>>                - const: ahb # AHB Reset
> >>>>>>                - const: axi_m_sticky # AXI Master Sticky reset
> >>>>>> +  - if:
> >>>>>> +      properties:
> >>>>>> +        compatible:
> >>>>>> +          contains:
> >>>>>> +            enum:
> >>>>>> +              - qcom,pcie-ipq9574
> >>>>>> +    then:
> >>>>>> +      properties:
> >>>>>> +        clocks:
> >>>>>> +          minItems: 6
> >>>>>> +          maxItems: 6
> >>>>>> +        clock-names:
> >>>>>> +          items:
> >>>>>> +            - const: ahb  # AHB clock
> >>>>>> +            - const: aux  # Auxiliary clock
> >>>>>> +            - const: axi_m # AXI Master clock
> >>>>>> +            - const: axi_s # AXI Slave clock
> >>>>>> +            - const: axi_bridge # AXI bridge clock
> >>>>>> +            - const: rchng
> >>>>>> +        resets:
> >>>>>> +          minItems: 8
> >>>>>> +          maxItems: 8
> >>>>>> +        reset-names:
> >>>>>> +          items:
> >>>>>> +            - const: pipe # PIPE reset
> >>>>>> +            - const: sticky # Core Sticky reset
> >>>>>> +            - const: axi_s_sticky # AXI Slave Sticky reset
> >>>>>> +            - const: axi_s # AXI Slave reset
> >>>>>> +            - const: axi_m_sticky # AXI Master Sticky reset
> >>>>>> +            - const: axi_m # AXI Master reset
> >>>>>> +            - const: aux # AUX Reset
> >>>>>> +            - const: ahb # AHB Reset
> >>>>>> +
> >>>>>>      - if:
> >>>>>>          properties:
> >>>>>>            compatible:
> >>>>>> @@ -681,6 +738,16 @@ allOf:
> >>>>>>            - interconnects
> >>>>>>            - interconnect-names
> >>>>>> +  - if:
> >>>>>> +      properties:
> >>>>>> +        compatible:
> >>>>>> +          contains:
> >>>>>> +            enum:
> >>>>>> +              - qcom,pcie-ipq9574
> >>>>>> +    then:
> >>>>>> +      required:
> >>>>>> +        - msi-parent
> >>>>>> +
> >>>>>>      - if:
> >>>>>>          not:
> >>>>>>            properties:
> >>>>>> @@ -693,6 +760,7 @@ allOf:
> >>>>>>                    - qcom,pcie-ipq8064v2
> >>>>>>                    - qcom,pcie-ipq8074
> >>>>>>                    - qcom,pcie-ipq8074-gen3
> >>>>>> +                - qcom,pcie-ipq9574
> >>>>>>                    - qcom,pcie-qcs404
> >>>>>>        then:
> >>>>>>          required:
> >>>>>> --
> >>>>>> 2.17.1
> >>>>>>
> >>>>>
> >>>> Thanks,
> >>>> Devi Priya
> >>>
> >>
> >
> Thanks,
> Devi Priya



-- 
With best wishes
Dmitry