[cc->to: Rob]

On Fri, Feb 21, 2025 at 11:29:20AM +0800, Chen Wang wrote:

On 2025/2/20 2:22, Bjorn Helgaas wrote:

quoted

On Wed, Feb 12, 2025 at 01:54:11PM +0800, Chen Wang wrote:

quoted

On 2025/2/12 12:25, Bjorn Helgaas wrote:
[......]

quoted

quoted

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.

Looks good.  It would be nice if there were some naming similarity or
comment or other hint to connect sophgo,core-id with the syscon node.

quoted

pcie_rc1: pcie@7062000000 {
     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@7062800000 {
     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@7063800000 {
     compatible = "sophgo,sg2042-pcie-ctrl", "syscon";
     reg = <0x70 0x63800000 0x0 0x800000>;
};

I find dtb check will report error due to "port" is not a evaulated property
for pcie host. Should we add a vendror specific property for this?

Or do you have any example for reference?

Sorry, I don't know enough about dtb to answer this.  Maybe Rob?