linux-kernel - Re: [PATCH 1/2] dt-bindings: PCI: qcom,pcie-ep-sa8255p: Document firmware managed PCIe endpoint

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Message-ID: <20251205-majestic-guillemot-of-criticism-80c18b@quoll>
Date: Fri, 5 Dec 2025 10:10:03 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Mrinmay Sarkar <mrinmay.sarkar@....qualcomm.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, 
	Lorenzo Pieralisi <lpieralisi@...nel.org>, Krzysztof Wilczyński <kwilczynski@...nel.org>, 
	Manivannan Sadhasivam <mani@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, kernel@....qualcomm.com, 
	Manivannan Sadhasivam <manivannan.sadhasivam@....qualcomm.com>, Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>, 
	quic_vbadigan@...cinc.com, quic_shazhuss@...cinc.com, konrad.dybcio@....qualcomm.com, 
	Rama Krishna <quic_ramkri@...cinc.com>, Ayiluri Naga Rashmi <quic_nayiluri@...cinc.com>, 
	Nitesh Gupta <quic_nitegupt@...cinc.com>
Subject: Re: [PATCH 1/2] dt-bindings: PCI: qcom,pcie-ep-sa8255p: Document
 firmware managed PCIe endpoint

On Wed, Dec 03, 2025 at 06:56:47PM +0530, Mrinmay Sarkar wrote:
> Document the required configuration to enable the PCIe Endpoint controller
> on SA8255p which is managed by firmware using power-domain based handling.
> 
> Signed-off-by: Mrinmay Sarkar <mrinmay.sarkar@....qualcomm.com>
> ---
>  .../bindings/pci/qcom,pcie-ep-sa8255p.yaml         | 114 +++++++++++++++++++++

Filename must match the compatible. In your case, the filename is
correct but you wanted old format for the compatible (so compatible
should be rewritten to match filename).

>  1 file changed, 114 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/qcom,pcie-ep-sa8255p.yaml b/Documentation/devicetree/bindings/pci/qcom,pcie-ep-sa8255p.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..970f65d46c8e2fa4c44665cb7a346dea1dc9e06a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pci/qcom,pcie-ep-sa8255p.yaml
> @@ -0,0 +1,114 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pci/qcom,pcie-ep-sa8255p.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm firmware managed PCIe Endpoint Controller
> +
> +description:
> +  Qualcomm SA8255p SoC PCIe endpoint controller is based on the Synopsys
> +  DesignWare PCIe IP which is managed by firmware.
> +
> +maintainers:
> +  - Manivannan Sadhasivam <mani@...nel.org>
> +
> +properties:
> +  compatible:
> +    const: qcom,sa8255p-pcie-ep
> +
> +  reg:
> +    minItems: 6

Why is this flexible?

> +    items:
> +      - description: Qualcomm-specific PARF configuration registers
> +      - description: DesignWare PCIe registers
> +      - description: External local bus interface registers
> +      - description: Address Translation Unit (ATU) registers
> +      - description: Memory region used to map remote RC address space
> +      - description: BAR memory region
> +      - description: DMA register space
> +
> +  reg-names:
> +    minItems: 6
> +    items:
> +      - const: parf
> +      - const: dbi
> +      - const: elbi
> +      - const: atu
> +      - const: addr_space
> +      - const: mmio
> +      - const: dma
> +
> +  interrupts:
> +    minItems: 2

And this/

> +    items:
> +      - description: PCIe Global interrupt
> +      - description: PCIe Doorbell interrupt
> +      - description: DMA interrupt
> +
> +  interrupt-names:
> +    minItems: 2
> +    items:
> +      - const: global
> +      - const: doorbell
> +      - const: dma
> +
> +  iommus:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    description: GPIO used as PERST# input signal
> +    maxItems: 1
> +
> +  wake-gpios:
> +    description: GPIO used as WAKE# output signal
> +    maxItems: 1
> +
> +  power-domains:
> +    maxItems: 1
> +
> +  dma-coherent: true
> +
> +  num-lanes:
> +    default: 2

Isn't this deducible from the compatible? Do you have have different
PCIe controllers with different lanes?


> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - interrupts
> +  - interrupt-names
> +  - reset-gpios
> +  - power-domains
> +
> +additionalProperties: false

Best regards,
Krzysztof