linux-kernel - Re: [PATCH v3 1/5] dt-bindings: pci: Add Sophgo SG2042 PCIe host

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Message-ID:
 <MA0PR01MB5671F42DEE2C5491A65E3975FEFB2@MA0PR01MB5671.INDPRD01.PROD.OUTLOOK.COM>
Date: Mon, 17 Feb 2025 16:40:16 +0800
From: Chen Wang <unicorn_wang@...look.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Chen Wang <unicornxw@...il.com>, kw@...ux.com,
 u.kleine-koenig@...libre.com, aou@...s.berkeley.edu, arnd@...db.de,
 bhelgaas@...gle.com, conor+dt@...nel.org, guoren@...nel.org,
 inochiama@...look.com, krzk+dt@...nel.org, lee@...nel.org,
 lpieralisi@...nel.org, manivannan.sadhasivam@...aro.org, palmer@...belt.com,
 paul.walmsley@...ive.com, pbrobinson@...il.com, robh@...nel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-pci@...r.kernel.org, linux-riscv@...ts.infradead.org,
 chao.wei@...hgo.com, xiaoguang.xing@...hgo.com, fengchun.li@...hgo.com
Subject: Re: [PATCH v3 1/5] dt-bindings: pci: Add Sophgo SG2042 PCIe host

Hello, Bjorn, what do you think of my input?

Regards,

Chen

On 2025/2/12 13:54, Chen Wang wrote:
>
> On 2025/2/12 12:25, Bjorn Helgaas wrote:
> [......]
>>> pcie_rc1 and pcie_rc2 share registers in cdns_pcie1_ctrl. By using
>>> different "sophgo,core-id" values, they can distinguish and access
>>> the registers they need in cdns_pcie1_ctrl.
>> Where does cdns_pcie1_ctrl fit in this example?  Does that enclose
>> both pcie_rc1 and pcie_rc2?
>
> cdns_pcie1_ctrl is defined as a syscon node,  which contains registers 
> shared by pcie_rc1 and pcie_rc2. In the binding yaml file, I drew a 
> diagram to describe the relationship between them, copy here for your 
> quick reference:
>
> +                     +-- Core (Link0) <---> pcie_rc1 +-----------------+
> +                     | |                 |
> +      Cadence IP 2 --+                                | 
> cdns_pcie1_ctrl |
> +                     | |                 |
> +                     +-- Core (Link1) <---> pcie_rc2 +-----------------+
>
> The following is an example with cdns_pcie1_ctrl added. For 
> simplicity, I deleted pcie_rc0.
>
> pcie_rc1: pcie@...2000000 {
>     compatible = "sophgo,sg2042-pcie-host";
>     ...... // host bride level properties
>     linux,pci-domain = <1>;
>     sophgo,core-id = <0>;
>     sophgo,syscon-pcie-ctrl = <&cdns_pcie1_ctrl>;
>     port {
>         // port level properties
>         vendor-id = <0x1f1c>;
>         device-id = <0x2042>;
>         num-lanes = <2>;
>     };
> };
>
> pcie_rc2: pcie@...2800000 {
>     compatible = "sophgo,sg2042-pcie-host";
>     ...... // host bride level properties
>     linux,pci-domain = <2>;
>     sophgo,core-id = <1>;
>     sophgo,syscon-pcie-ctrl = <&cdns_pcie1_ctrl>;
>     port {
>         // port level properties
>         vendor-id = <0x1f1c>;
>         device-id = <0x2042>;
>         num-lanes = <2>;
>     }
>
> };
>
> cdns_pcie1_ctrl: syscon@...3800000 {
>     compatible = "sophgo,sg2042-pcie-ctrl", "syscon";
>     reg = <0x70 0x63800000 0x0 0x800000>;
> };
>
>
> _______________________________________________
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