Re: [PATCH] arm64: dts: rockchip: Enable USB device mode on rk3399-roc-pc-plus

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Adding `usb-role-switch` breaks existing host mode and automatic OTG role switching for the DWC3 controller due to a missing OF graph connection.
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--- Patch [1]: [PATCH] arm64: dts: rockchip: Enable USB device mode on rk3399-roc-pc-plus ---
commit 083559b8c4d210ad85e3dc07a4f89e6cd4079c56
Author: Fabio Estevam <festevam@nabladev.com>

arm64: dts: rockchip: Enable USB device mode on rk3399-roc-pc-plus

This commit describes the DWC3 controller as a USB role switch and selects
peripheral as the default role. This allows DWC3 to register a UDC while
retaining OTG operation.

> diff --git a/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus.dts b/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus.dts
> --- a/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3399-roc-pc-plus.dts

[ ... ]

> @@ -203,7 +203,9 @@ &uart0 {
>  };
>  
>  &usbdrd_dwc3_0 {
> -	dr_mode = "host";
> +	dr_mode = "otg";
> +	role-switch-default-mode = "peripheral";
> +	usb-role-switch;

[Severity: High]
Does adding the usb-role-switch property here break existing host mode
functionality on the Type-C port?

When usb-role-switch is present, dwc3_drd_init() bypasses its internal
hardware OTG initialization and waits indefinitely for a software role switch
event.

Without an OF graph connection (a port/endpoint mapping) from the fusb0
Type-C controller to this dwc3 node, the tcpm framework won't be able to
locate the USB role switch via fwnode_usb_role_switch_get() when a user
plugs in a host adapter.

As a result, the role switch lookup fails and the controller might get
permanently stuck in the default peripheral mode.

Should an OF graph connection be added between the Type-C controller and
this dwc3 node so the role switch events can be delivered correctly?

>  	status = "okay";
>  };

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Sashiko AI review · https://sashiko.dev/#/patchset/20260721030043.84691-1-festevam@gmail.com?part=1