Re: [PATCH] usb: core: support interface node for simple USB devices

[Greg KH]

On Wed, Jan 22, 2025 at 02:47:32PM +0100, Catalin Popescu wrote:
> A simple usb device has a single configuration and a single interface
> and is considered as a "combined node" when defined in the devicetree.
> If available, its interface node is simply ignored which is a problem
> whenever the interface node has subnodes. To prevent that from happening
> first check for any subnode and ignore the interface node only if no
> subnode was found.
> 
> Example: FTDI chip FT234XD that has only one UART interface which is
> being used as a serdev by other driver.
> 
> device@1 {
> 	compatible = "usb403,6015";
> 	reg = <1>;
> 
> 	#address-cells = <2>;
> 	#size-cells = <0>;
> 
> 	interface@0 {
> 		compatible = "usbif403,6015.config1.0";
> 		reg = <0 1>;
> 
> 		bluetooth {
> 			compatible = "nxp,88w8987-bt";
> 		};
> 	};
> };

serdev can not use usb-serial devices due to the lack of hotplugging, so
why is this an issue?  I thought that just would not work.

confused,

greg k-h