linux-kernel - Re: [PATCH v2 1/8] dt-bindings: PCI: Add binding for qps615

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Message-ID: <100e27d7-2714-89ca-4a98-fccaa5b07be3@quicinc.com>
Date: Mon, 5 Aug 2024 10:56:46 +0530
From: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Lorenzo Pieralisi
	<lpieralisi@...nel.org>,
        Krzysztof Wilczyński
	<kw@...ux.com>,
        Rob Herring <robh@...nel.org>, Bjorn Helgaas
	<bhelgaas@...gle.com>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        <cros-qcom-dts-watchers@...omium.org>,
        Bartosz Golaszewski <brgl@...ev.pl>, Jingoo Han <jingoohan1@...il.com>,
        Manivannan Sadhasivam
	<manivannan.sadhasivam@...aro.org>
CC: <andersson@...nel.org>, <quic_vbadigan@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Bartosz
 Golaszewski" <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 1/8] dt-bindings: PCI: Add binding for qps615



On 8/5/2024 10:44 AM, Krzysztof Kozlowski wrote:
> On 05/08/2024 06:11, Krishna Chaitanya Chundru wrote:
> 
> 
>>>> +
>>>> +  qcom,nfts:
>>>> +    $ref: /schemas/types.yaml#/definitions/uint8
>>>> +    description:
>>>> +      Fast Training Sequence (FTS) is the mechanism that
>>>> +      is used for bit and Symbol lock.
>>>
>>> What are the values? Why this is uint8?
>>>
>> These represents number of fast training sequence and doesn't have
>> any units and the maximum value for this is 0xFF only so we used
>> uint8.
>>> You described the desired Linux feature or behavior, not the actual
>>> hardware. The bindings are about the latter, so instead you need to
>>> rephrase the property and its description to match actual hardware
>>> capabilities/features/configuration etc.
>> ack.
>>>
>>>> +
>>>> +allOf:
>>>> +  - $ref: /schemas/pci/pci-bus-common.yaml#
>>>> +  - if:
>>>> +      properties:
>>>> +        compatible:
>>>> +          contains:
>>>> +            const: pci1179,0623
>>>> +      required:
>>>> +        - compatible
>>>
>>> Why do you have entire if? You do not have multiple variants, drop.
>>>
>> The child nodes also referencing the qcom,qps615.yaml# node, I tried
>> to use this way to say "the below properties are for the required for
>> parent and optional for child".
> 
> I don't understand how child device can be exactly the same as parent
> device. How does it look in terms of hardware? Pins and supplies?
> 
>>>> +    then:
>>>> +      required:
>>>> +        - vdd18-supply
>>>> +        - vdd09-supply
>>>> +        - vddc-supply
>>>> +        - vddio1-supply
>>>> +        - vddio2-supply
>>>> +        - vddio18-supply
>>>> +        - qcom,qps615-controller
>>>> +        - reset-gpios
>>>> +
>>>> +patternProperties:
>>>> +  "@1?[0-9a-f](,[0-7])?$":
>>>> +    type: object
>>>> +    $ref: qcom,qps615.yaml#
>>>> +    additionalProperties: true
>>>
>>> Nope, drop pattern Properties or explain what is this.
>>>
>> the child nodes represent the downstream ports of the PCIe
>> switch which wants to use same properties that is why
>> I tried to use this pattern properties.
> 
> Downstream port is not the same as device. Why downstream port has the
> same supplies? To which pins are they connected?
> 
> 
Hi Krzysztof,

Downstream ports dosen't have pins or supplies to power on.

But there are properties like qcom,l0s-entry-delay-ns,
qcom,l1-entry-delay-ns,  qcom,tx-amplitude-millivolt etc which
applicable for child nodes also. Instead of re-declaring the
these properties again I tried to use pattern properties.

- krishna Chaitanya.
> 
> 
> Best regards,
> Krzysztof
>