On Sat, Mar 21, 2020 at 09:24:42PM +0100, Tobias Waldekranz wrote:

Describe how the USB to MDIO controller can optionally use device tree
bindings to reference attached devices such as switches.

Looks like this is in linux-next now. First I'm seeing it because the DT 
list was not Cc'ed.

This is breaking 'make dt_binding_check'. Revert or fix before this goes 
to Linus please.

New bindings should be:

(GPL-2.0-only OR BSD-2-Clause)

+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/marvell,mvusb.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Marvell USB to MDIO Controller
+
+maintainers:
+  - Tobias Waldekranz [off-list ref]
+
+description: |+
+  This controller is mounted on development boards for Marvell's Link Street
+  family of Ethernet switches. It allows you to configure the switch's registers
+  using the standard MDIO interface.
+
+  Since the device is connected over USB, there is no strict requirement of
+  having a device tree representation of the device. But in order to use it with
+  the mv88e6xxx driver, you need a device tree node in which to place the switch
+  definition.
+
+allOf:
+  - $ref: "mdio.yaml#"
+
+properties:
+  compatible:
+    const: usb1286,1fa4
+  reg:
+    maxItems: 1
+    description: The USB port number on the host controller

Really, it's the port on the hub which could be a root hub.

+
+required:
+  - compatible
+  - reg
+  - "#address-cells"
+  - "#size-cells"
+
+examples:
+  - |
+    /* USB host controller */
+    &usb1 {

This won't compile because there's no 'usb1' to reference.

+            mvusb: mdio@1 {
+                    compatible = "usb1286,1fa4";
+                    reg = <1>;
+                    #address-cells = <1>;
+                    #size-cells = <0>;
+            };
+    };
+
+    /* MV88E6390X devboard */
+    &mvusb {

Move this into the above node.

+            switch@0 {
+                    compatible = "marvell,mv88e6190";
+                    status = "ok";

Don't show status in examples.

+                    reg = <0x0>;
+
+                    ports {
+                            /* Port definitions */

Incomplete examples will eventually fail as when complete schema are 
present.