Re: [PATCH 7/8] i2c: core: clean up bus id allocation

[Johan Hovold <johan@kernel.org>]

On Tue, May 05, 2026 at 04:25:46PM +0200, Johan Hovold wrote:
> Clean up bus id allocation by using a common helper and deferring it
> until it is needed during adapter registration.
> 
> Signed-off-by: Johan Hovold <johan@kernel.org>

> @@ -1665,17 +1675,8 @@ int i2c_add_adapter(struct i2c_adapter *adapter)
>  	int id;
>  
>  	id = of_alias_get_id(dev->of_node, "i2c");
> -	if (id >= 0) {
> -		adapter->nr = id;
> -		return __i2c_add_numbered_adapter(adapter);
> -	}
> -
> -	mutex_lock(&core_lock);
> -	id = idr_alloc(&i2c_adapter_idr, NULL,
> -		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
> -	mutex_unlock(&core_lock);
> -	if (WARN(id < 0, "couldn't get idr"))
> -		return id;
> +	if (id < 0)
> +		id = -1;
>  
>  	adapter->nr = id;
>  
> @@ -1708,10 +1709,7 @@ EXPORT_SYMBOL(i2c_add_adapter);
>   */
>  int i2c_add_numbered_adapter(struct i2c_adapter *adap)
>  {
> -	if (adap->nr == -1) /* -1 means dynamically assign bus id */
> -		return i2c_add_adapter(adap);

Sashiko also flagged this a potential issue -- needs to be kept for the
alias lookup.

> -
> -	return __i2c_add_numbered_adapter(adap);
> +	return i2c_register_adapter(adap);

Johan