Re: [PATCH v6 06/16] usb: hub: Associate port@ fwnode with USB port device

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 7/21/26 8:54 AM, Chen-Yu Tsai wrote:
> When a USB hub port is connected to a connector in a firmware node
> graph, the port itself has a node in the graph.
> 
> Associate the port's firmware node with the USB port's device,
> usb_port::dev. This is used in later changes for the M.2 slot power
> sequencing provider to match against the requesting port.
> 
> To avoid potential conflicts with ACPI firmware nodes and then causing
> power management issues, only assign the firmware node if the hub's
> firmware node is not an ACPI firmware node.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
> ---

[...]

> +	/*
> +	 * ACPI FW nodes are associated later when device_register() happens.
> +	 * Skip assigning one here to avoid potential conflicts.
> +	 */
> +	if (!is_acpi_node(fwnode)) {
> +		struct fwnode_handle *port;
> +
> +		/*
> +		 * fwnode_graph_get_port_by_id() returns either a valid fwnode handle
> +		 * or NULL. Passing NULL to device_set_node() clears any associated
> +		 * fwnode. It is effectively a no-op here, since no fwnode has been
> +		 * assigned to the newly created device yet.
> +		 */
> +		port = fwnode_graph_get_port_by_id(fwnode, port1, FWNODE_GRAPH_DEVICE_DISABLED);

This works if the node at the other end of the graph is a
USB hub, e.g. from qcom/lemans-evk.dts:

usb_hub_3_x: hub@2 {
	compatible = "usb5e3,625";
	reg = <2>;

	peer-hub = <&usb_hub_2_x>;

	ports {
		#address-cells = <1>;
		#size-cells = <0>;

		port@1 {
			reg = <1>;

			usb_hub_3_1: endpoint {
				remote-endpoint = <&hd3ss3220_1_out_ep>;
			};
		};

		port@4 {
			reg = <4>;

			usb_hub_3_4: endpoint {
			};
		};
	};
};

But something I faced when I was poking at USB4 was that dt-bindings
currently assume every controller is effectively single-port and the
of_graph ports under it represent HS/SS lanes, i.e. the entire
"ports" subnode represents a single USB port

I think the solution here would be to do ports {} under the controller
and have every one of them have 2 endpoints (for HS and SS
respectively) - then, each DT-port would correspond to a USB port
(sorta like in the hub case, minus the hubs are split for HS/SS so
they have just a single endpoint under each port)

But that comes with a big breakage, as always..

Konrad