On Wed, Oct 27, 2021 at 4:54 PM Rob Herring [off-list ref] wrote:

On Tue, Oct 26, 2021 at 4:27 PM Jim Quinlan [off-list ref] wrote:

quoted

On Mon, Oct 25, 2021 at 6:24 PM Rob Herring [off-list ref] wrote:

quoted

On Fri, Oct 22, 2021 at 10:06:54AM -0400, Jim Quinlan wrote:

quoted

Similar to the regulator bindings found in "rockchip-pcie-host.txt", this
allows optional regulators to be attached and controlled by the PCIe RC
driver.  That being said, this driver searches in the DT subnode (the EP
node, eg pci@0,0) for the regulator property.

The use of a regulator property in the pcie EP subnode such as
"vpcie12v-supply" depends on a pending pullreq to the pci-bus.yaml
file at

https://github.com/devicetree-org/dt-schema/pull/54

Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
---
 .../bindings/pci/brcm,stb-pcie.yaml           | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
index b9589a0daa5c..fec13e4f6eda 100644
--- a/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/brcm,stb-pcie.yaml

@@ -154,5 +154,28 @@ examples:
                                  <0x42000000 0x1 0x80000000 0x3 0x00000000 0x0 0x80000000>;
                     brcm,enable-ssc;
                     brcm,scb-sizes =  <0x0000000080000000 0x0000000080000000>;
+
+                    /* PCIe bridge */

More specifically, the root port.

quoted

+                    pci@0,0 {
+                            #address-cells = <3>;
+                            #size-cells = <2>;
+                            reg = <0x0 0x0 0x0 0x0 0x0>;
+                            device_type = "pci";
+                            ranges;
+
+                            /* PCIe endpoint */
+                            pci@0,0 {
+                                    device_type = "pci";

This means this device is a PCI bridge which wouldn't typically be the
endpoint. Is that intended?

Hi Rob,

I'm not sure I understand what you are saying --  do you want the
innermost node to be named something like ep-pci@0,0, and its
containing node pci-bridge@0,0?   Or, more likely, I'm missing the
point.  If my DT subtree is this

I'm confused as to how a bridge is the endpoint. If it is a bridge
(which 'device_type = "pci"' means it is), then there should be
another PCI device under it. That may or may not have a DT node.

I did not know that device_type="pci" implies that it must be a
bridge;  [1] says "device_type" is deprecated  for PCI and [2] defers
to Open Firmware EEE 1275, which is not free AFAICT. Do you have
better URLs that describe this?  At any rate, I will remove the
device_type="pci" from the innermost DT node, and resubmit.

quoted

pcie@8b10000 {
    compatible = "brcm,bcm7278-pcie";
    ....
    pci-bridge@0,0 {
        reg = <0x0 0x0 0x0 0x0 0x0>; /* bus 0 */
        .....
        pci-ep@0,0,0 {
            reg = <0x10000 0x0 0x0 0x0 0x0>;  /* bus 1 */
            vpcie3v3-supply = <&vreg8>;
            ...
        }
    }
}

then the of_nodes appear to align correctly with the devices:

$ cd /sys/devices/platform/
$ cat 8b10000.pcie/of_node/name
pcie
$ cat 8b10000.pcie/pci0000:00/0000:00:00.0/of_node
pci-bridge
$ cat 8b10000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/of_node/name
pci-ep

What does 'lspci -tv' show?

$ lspci -tv
-+-[0000:01]---00.0  Intel Corporation Wireless 7260
  \-[0000:00]---00.0  Broadcom Inc. and subsidiaries Device 7278

quoted

and the EP device works of course.  I've even printed out the
device_node structure in the EP driver's probe and it is as expected.
I've noticed that examples such as
"arch/arm64/boot/dts/nvidia/tegra186.dtsi" have the EP node (eg
pci@1,0) directly under the
host bridge DT node (pcie@10003000).  I did try doing that, but the EP
device's probe is given a NUL device_node pointer.

If you want a complex example I know that's right, then see hikey970.

Thanks, will look.

Jim

[1] https://buildmedia.readthedocs.org/media/pdf/devicetree-specification/latest/devicetree-specification.pdf
[2] https://www.openfirmware.info/data/docs/bus.pci.pdf

Rob