On Mon, Aug 30, 2021 at 11:45 AM [off-list ref] wrote:

On Mon, 2021-08-30 at 08:39 -0500, Rob Herring wrote:

quoted

On Mon, Aug 30, 2021 at 12:39:09PM +0200, Nicolas Saenz Julienne wrote:

quoted

dtbs_check currently complains that:

arch/arm/boot/dts/bcm2711-rpi-4-b.dts:220.10-231.4: Warning
(pci_device_reg): /scb/pcie@7d500000/pci@1,0: PCI unit address format
error, expected "0,0"

Unsurprisingly pci@0,0 is the right address, as illustrated by its reg
property:

    &pcie0 {
            pci@0,0 {
                    /*
                     * As defined in the IEEE Std 1275-1994 document,
                     * reg is a five-cell address encoded as (phys.hi
                     * phys.mid phys.lo size.hi size.lo). phys.hi
                     * should contain the device's BDF as 0b00000000
                     * bbbbbbbb dddddfff 00000000. The other cells
                     * should be zero.
                     */
                    reg = <0 0 0 0 0>;
            };
    };

The bus is clearly 0. So fix it.

s/bus/device/

The unit-address format is '<device>,<function>' (and function is
optional). The bus number is not part of the unit-address because that
is dynamic and then the path would not be fixed/known. The bus is part
of 'reg' for true OpenFirmware, but for FDT I think it should always be
0 as the DT is static.

Looks like the child node is wrong (both unit-address and reg) as well:

                usb@1,0 {
                        reg = <0x10000 0 0 0 0>;
                        resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
                };

It doesn't warn because the bridge node is also missing 'device_type =
"pci";'.

This is all fairly hard to get right (see recent hikey970 patches for a
complex example). I'm thinking about writing a tool that generates a DT
with PCI nodes by reading the PCI hierachy from sysfs.

Just to double-check I understood everything, with:

        lspci -D -PP
        0000:00:00.0 PCI bridge: Broadcom Inc. and subsidiaries BCM2711 PCIe Bridge (rev 10)
        0000:00:00.0/01:00.0 USB controller: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller (rev 01)

It should look like this:

        &pcie0 {
                pci@0,0 {
                        device_type = "pci";
                        #address-cells = <3>;
                        #size-cells = <2>;
                        ranges;

                        reg = <0 0 0 0 0>;

                        usb@0,0 {
                                reg = <0 0 0 0 0>;
                                resets = <&reset RASPBERRYPI_FIRMWARE_RESET_ID_USB>;
                        };
                };
        };

Yes, that looks correct.

Rob