Re: [PATCH v9 4/8] usb: misc: qcom_eud: add per-path role switch support

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

On 9/29/26 11:35 PM, Elson Serrao wrote:
> The EUD hardware can support multiple High-Speed USB paths, each connected
> to different USB controllers. The current implementation uses a single
> chip-level role switch, which cannot properly handle multi-path
> configurations where each path needs independent role management. Since
> EUD is physically present between the USB connector and the controller,
> it should also relay the role change requests from the connector.
> 
> Restructure the driver to support per-path role switches and remove the
> chip-level role switch. Additionally, as EUD need not modify the USB
> role upon enabling, remove the unnecessary role switch call from
> enable_eud().
> 
> Reviewed-by: Peter Chen <peter.chen@kernel.org>
> Signed-off-by: Elson Serrao <elson.serrao@oss.qualcomm.com>
> ---

[...]

> -static void eud_role_switch_release(void *data)
> +static int eud_role_switch_set(struct usb_role_switch *sw, enum usb_role role)
>  {
> -	struct eud_chip *chip = data;
> +	struct eud_path *path = usb_role_switch_get_drvdata(sw);
> +	int ret;
> +
> +	/* curr_role tracks the role from EUD's point of view */
> +	path->curr_role = role;

This should be assigned after the fallible call below

Konrad

> +
> +	/* Forward the role request to the USB controller */
> +	ret = usb_role_switch_set_role(path->controller_sw, role);
> +	if (ret) {
> +		dev_err(path->chip->dev, "failed to set role %s for port %u: %d\n",
> +			usb_role_string(role), path->num, ret);
> +		return ret;
> +	}
>  
> -	usb_role_switch_put(chip->role_sw);
> +	return 0;
> +}
> +
> +static void eud_path_role_switch_release(void *data)
> +{
> +	struct eud_path *path = data;
> +
> +	usb_role_switch_unregister(path->eud_sw);
> +	usb_role_switch_put(path->controller_sw);
> +	of_node_put(path->np);
>  }
>  
>  static int eud_init_path(struct eud_chip *chip, struct device_node *np)
>  {
> +	struct usb_role_switch_desc role_sw_desc = {NULL};
> +	struct usb_role_switch *sw;
>  	struct device_node *controller_node;
>  	struct eud_path *path;
> +	const char *dr_mode = "";
>  	u32 path_num;
>  	int ret;
>  
> @@ -328,14 +359,61 @@ static int eud_init_path(struct eud_chip *chip, struct device_node *np)
>  				     "failed to get controller node for path %u\n", path_num);
>  
>  	path->phy = devm_of_phy_get_by_index(chip->dev, controller_node, 0);
> -	of_node_put(controller_node);
> -
> -	if (IS_ERR(path->phy))
> +	if (IS_ERR(path->phy)) {
> +		of_node_put(controller_node);
>  		return dev_err_probe(chip->dev, PTR_ERR(path->phy),
>  				     "failed to get PHY for path %d\n", path_num);
> +	}
>  
>  	chip->paths[path_num] = path;
>  
> +	of_property_read_string(controller_node, "dr_mode", &dr_mode);
> +
> +	/* No role switch needed for fixed role controllers */
> +	if (!strcmp(dr_mode, "host")) {
> +		path->curr_role = USB_ROLE_HOST;
> +		of_node_put(controller_node);
> +		return 0;
> +	}
> +
> +	if (!strcmp(dr_mode, "peripheral")) {
> +		path->curr_role = USB_ROLE_DEVICE;
> +		of_node_put(controller_node);
> +		return 0;
> +	}
> +
> +	path->curr_role = USB_ROLE_NONE;
> +
> +	sw = usb_role_switch_find_by_fwnode(of_fwnode_handle(controller_node));
> +	if (!sw) {
> +		of_node_put(controller_node);
> +		return dev_err_probe(chip->dev, -EPROBE_DEFER,
> +				     "Failed to get controller role switch for path %d\n",
> +				     path_num);
> +	}
> +	path->controller_sw = sw;
> +
> +	of_node_put(controller_node);
> +
> +	path->np = of_node_get(np);
> +	role_sw_desc.fwnode = of_fwnode_handle(path->np);
> +	role_sw_desc.set = eud_role_switch_set;
> +	role_sw_desc.driver_data = path;
> +	snprintf(path->name, sizeof(path->name), "eud-path%u", path_num);
> +	role_sw_desc.name = path->name;
> +
> +	path->eud_sw = usb_role_switch_register(chip->dev, &role_sw_desc);
> +	if (IS_ERR(path->eud_sw)) {
> +		usb_role_switch_put(path->controller_sw);
> +		of_node_put(path->np);
> +		return dev_err_probe(chip->dev, PTR_ERR(path->eud_sw),
> +				     "Failed to register EUD role switch for path %d\n", path_num);
> +	}
> +
> +	ret = devm_add_action_or_reset(chip->dev, eud_path_role_switch_release, path);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  }
>  
> @@ -352,15 +430,6 @@ static int eud_probe(struct platform_device *pdev)
>  
>  	chip->dev = &pdev->dev;
>  
> -	chip->role_sw = usb_role_switch_get(&pdev->dev);
> -	if (IS_ERR(chip->role_sw))
> -		return dev_err_probe(chip->dev, PTR_ERR(chip->role_sw),
> -					"failed to get role switch\n");
> -
> -	ret = devm_add_action_or_reset(chip->dev, eud_role_switch_release, chip);
> -	if (ret)
> -		return ret;
> -
>  	chip->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(chip->base))
>  		return PTR_ERR(chip->base);