Re: [PATCH v8 2/2] i2c: mux: Propagate firmware nodes to channel adapters

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Mon, Aug 31, 2026 at 10:22:07AM -0700, Ahmad Byagowi wrote:
> Device Tree channel nodes are associated with the adapters created by
> i2c-mux, but equivalent firmware-node descriptions are not.
> 
> Use generic firmware-node operations for the existing channel lookup
> and associate the returned node with the adapter. Do not restrict the
> lookup by firmware-node type, so Device Tree, software nodes, and ACPI
> descriptions all follow the same property traversal. The existing
> acpi_preset_companion() call remains in place for the standard ACPI
> channel association.
> 
> Keep a separate reference to the node returned by the generic lookup
> because acpi_preset_companion() may replace the device's primary
> firmware node. Release the saved reference after adapter deletion.

...

>  	if (muxc->arbitrator)
> -		mux_node = of_get_child_by_name(dev_node, "i2c-arb");
> +		mux_node = fwnode_get_named_child_node(dev_node, "i2c-arb");
>  	else if (muxc->gate)
> -		mux_node = of_get_child_by_name(dev_node, "i2c-gate");
> +		mux_node = fwnode_get_named_child_node(dev_node, "i2c-gate");
>  	else
> -		mux_node = of_get_child_by_name(dev_node, "i2c-mux");
> +		mux_node = fwnode_get_named_child_node(dev_node, "i2c-mux");
>  
>  	if (mux_node) {
> -		/* A "reg" property indicates an old-style DT entry */
> -		if (!of_property_read_u32(mux_node, "reg", &reg)) {
> -			of_node_put(mux_node);
> +		/* A "reg" property indicates an old-style firmware entry. */
> +		if (!fwnode_property_read_u32(mux_node, "reg", &reg)) {
> +			fwnode_handle_put(mux_node);

Consider using __free(fwnode_handle) at some point. Perhaps as a patch
on top of this.

It also may help with the rest of the existing code elsewhere in the file.

>  			mux_node = NULL;
>  		}
>  	}
>  
>  	if (!mux_node)
> -		mux_node = of_node_get(dev_node);
> +		mux_node = fwnode_handle_get(dev_node);
>  	else if (muxc->arbitrator || muxc->gate)
>  		return mux_node;
>  
> -	for_each_child_of_node(mux_node, child) {
> -		ret = of_property_read_u32(child, "reg", &reg);
> +	fwnode_for_each_child_node(mux_node, child) {
> +		ret = fwnode_property_read_u32(child, "reg", &reg);
>  		if (ret)
>  			continue;
>  		if (chan_id == reg)
>  			break;
>  	}
>  
> -	of_node_put(mux_node);
> +	fwnode_handle_put(mux_node);
>  	return child;
>  }


-- 
With Best Regards,
Andy Shevchenko