linux-kernel - Re: [PATCH v1 1/2] dt-bindings: PCI: dwc: Add snps,skip-wait-link-up

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Message-ID: <b50ab99f-e307-3a66-9198-85a71b012e5e@linaro.org>
Date:   Fri, 24 Feb 2023 21:40:01 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Sajid Dalvi <sdalvi@...gle.com>, Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     kernel-team@...roid.com, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] dt-bindings: PCI: dwc: Add snps,skip-wait-link-up

On 24/02/2023 20:57, Sajid Dalvi wrote:
> When the Root Complex is probed, the default behavior is to spin in a loop
> waiting for the link to come up. In some systems the link is not brought up
> during probe, but later in the context of an end-point turning on.
> This property will allow the loop to be skipped.
> 
> Signed-off-by: Sajid Dalvi <sdalvi@...gle.com>
> ---

Thank you for your patch. There is something to discuss/improve.

>  Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
> index 1a83f0f65f19..0b8950a73b7e 100644
> --- a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
> +++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
> @@ -197,6 +197,14 @@ properties:
>        - contains:
>            const: msi
>  
> +  snps,skip-wait-link-up:
> +    $ref: /schemas/types.yaml#/definitions/flag
> +    description:
> +      When the Root Complex is probed, the default behavior is to spin in a
> +      loop waiting for the link to come up. In some systems the link is not
> +      brought up during probe, but later in the context of an end-point turning
> +      on. This property will allow the loop to be skipped.

I fail to see how probe behavior is related to properties of hardware.
You describe OS behavior, not hardware. This does not look like
belonging to DT.


Best regards,
Krzysztof