linux-kernel - Re: [PATCH v5 2/6] dt-bindings: PCI: qcom,pcie-sa8775p: document qcs8300

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Message-ID: <c91c5357-464b-4ecc-96a5-c617048f73e5@quicinc.com>
Date: Wed, 7 May 2025 17:56:12 +0800
From: Qiang Yu <quic_qianyu@...cinc.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Ziyue Zhang
	<quic_ziyuzhan@...cinc.com>
CC: <vkoul@...nel.org>, <kishon@...nel.org>, <robh@...nel.org>,
        <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
        <dmitry.baryshkov@...aro.org>, <neil.armstrong@...aro.org>,
        <abel.vesa@...aro.org>, <manivannan.sadhasivam@...aro.org>,
        <lpieralisi@...nel.org>, <kw@...ux.com>, <bhelgaas@...gle.com>,
        <andersson@...nel.org>, <konradybcio@...nel.org>,
        <linux-phy@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-pci@...r.kernel.org>, <quic_krichai@...cinc.com>,
        <quic_vbadigan@...cinc.com>
Subject: Re: [PATCH v5 2/6] dt-bindings: PCI: qcom,pcie-sa8775p: document
 qcs8300


On 5/7/2025 4:25 PM, Krzysztof Kozlowski wrote:
> On 07/05/2025 10:19, Ziyue Zhang wrote:
>> On 5/7/2025 1:10 PM, Krzysztof Kozlowski wrote:
>>> On Wed, May 07, 2025 at 11:10:15AM GMT, Ziyue Zhang wrote:
>>>> Add compatible for qcs8300 platform, with sa8775p as the fallback.
>>>>
>>>> Signed-off-by: Ziyue Zhang <quic_ziyuzhan@...cinc.com>
>>>> ---
>>>>    .../bindings/pci/qcom,pcie-sa8775p.yaml       | 26 ++++++++++++++-----
>>>>    1 file changed, 19 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/pci/qcom,pcie-sa8775p.yaml b/Documentation/devicetree/bindings/pci/qcom,pcie-sa8775p.yaml
>>>> index efde49d1bef8..154bb60be402 100644
>>>> --- a/Documentation/devicetree/bindings/pci/qcom,pcie-sa8775p.yaml
>>>> +++ b/Documentation/devicetree/bindings/pci/qcom,pcie-sa8775p.yaml
>>>> @@ -16,7 +16,12 @@ description:
>>>>    
>>>>    properties:
>>>>      compatible:
>>>> -    const: qcom,pcie-sa8775p
>>>> +    oneOf:
>>>> +      - const: qcom,pcie-sa8775p
>>>> +      - items:
>>>> +          - enum:
>>>> +              - qcom,pcie-qcs8300
>>>> +          - const: qcom,pcie-sa8775p
>>>>    
>>>>      reg:
>>>>        minItems: 6
>>>> @@ -45,7 +50,7 @@ properties:
>>>>    
>>>>      interrupts:
>>>>        minItems: 8
>>>> -    maxItems: 8
>>>> +    maxItems: 9
>>> I don't understand why this is flexible for sa8775p. I assume this
>>> wasn't tested or finished, just like your previous patch suggested.
>>>
>>> Please send complete bindings once you finish them or explain what
>>> exactly changed in the meantime.
>>>
>>> Best regards,
>>> Krzysztof
>> Hi Krzysztof
>> Global interrupt is optional in the PCIe driver. It is not present in
>> the SA8775p PCIe device tree node, but it is required for the QCS8300
> And hardware?

The PCIe controller on the SA8775p is also capable of generating a global
interrupt.
>> I did the DTBs and yaml checks before pushing this patch. This is how
>> I became aware that `maxItem` needed to be changed to 9.
> If it is required for QCS8300, then you are supposed to make it required
> in the binding for this device. Look at other bindings.

The global interrupt is not mandatory. The PCIe driver can still function
without this interrupt, but it will offer a better user experience when
the device is plugged in or removed. On other platforms, the global
interrupt is also optional, and `minItems` and `maxItems` are set to 8 and
9 respectively. Please refer to `qcom,pcie - sm8550.yaml`,
`qcom,pcie - sm8450.yaml`, and `qcom,pcie - x1e80100.yaml`.
>
> Best regards,
> Krzysztof

-- 
With best wishes
Qiang Yu