linux-kernel - Re: [PATCH v3 1/2] dt-bindings: PCI: amd-mdb: Add reset-gpios property for PCIe RP PERST# handling

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Message-ID: <29bdba7e-63f6-4084-901d-beaab0e74894@oss.qualcomm.com>
Date: Mon, 23 Jun 2025 13:21:57 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: Sai Krishna Musham <sai.krishna.musham@....com>, bhelgaas@...gle.com,
        lpieralisi@...nel.org, kw@...ux.com, mani@...nel.org, robh@...nel.org,
        krzk+dt@...nel.org, conor+dt@...nel.org, cassel@...nel.org
Cc: linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, michal.simek@....com,
        bharat.kumar.gogada@....com, thippeswamy.havalige@....com
Subject: Re: [PATCH v3 1/2] dt-bindings: PCI: amd-mdb: Add reset-gpios
 property for PCIe RP PERST# handling



On 6/18/2025 1:39 PM, Sai Krishna Musham wrote:
> Add support for the `reset-gpios` property in the PCIe Root Port (RP)
> child node to handle the PERST# signal via GPIO. Update the example
> to reflect this addition.
> 
> Signed-off-by: Sai Krishna Musham <sai.krishna.musham@....com>
> ---
> Changes in v3:
> - Move reset-gpios to PCI bridge node.
> 
> Changes in v2:
> - Update commit message
> ---
>   .../bindings/pci/amd,versal2-mdb-host.yaml    | 26 +++++++++++++++++++
>   1 file changed, 26 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> index 43dc2585c237..3ffe4512650d 100644
> --- a/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> +++ b/Documentation/devicetree/bindings/pci/amd,versal2-mdb-host.yaml
> @@ -71,6 +71,21 @@ properties:
>         - "#address-cells"
>         - "#interrupt-cells"
>   
> +patternProperties:
> +  '^pcie@[0-2],0$':
> +    type: object
> +    $ref: /schemas/pci/pci-pci-bridge.yaml#
> +
> +    properties:
> +      reg:
> +        maxItems: 1
> +
> +      reset-gpios:
> +        description: GPIO controlled connection to PERST# signal
> +        maxItems: 1
> +
This is already part of pci-bus-common.yaml in dtschema no need to
define it again here.

- Krishna Chaitanya.

> +    unevaluatedProperties: false
> +
>   required:
>     - reg
>     - reg-names
> @@ -87,6 +102,7 @@ examples:
>     - |
>       #include <dt-bindings/interrupt-controller/arm-gic.h>
>       #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/gpio/gpio.h>
>   
>       soc {
>           #address-cells = <2>;
> @@ -112,6 +128,16 @@ examples:
>               #size-cells = <2>;
>               #interrupt-cells = <1>;
>               device_type = "pci";
> +
> +            pcie@0,0 {
> +                device_type = "pci";
> +                reg = <0x0 0x0 0x0 0x0 0x0>;
> +                reset-gpios = <&tca6416_u37 7 GPIO_ACTIVE_LOW>;
> +                #address-cells = <3>;
> +                #size-cells = <2>;
> +                ranges;
> +            };
> +
>               pcie_intc_0: interrupt-controller {
>                   #address-cells = <0>;
>                   #interrupt-cells = <1>;