linux-kernel - Re: [RFC PATCH 3/3] i2c: i2c-core-of: Handle i2c bus extensions

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Message-ID: <71468d78-07aa-49b1-8b6d-3d98c6fc9893@kernel.org>
Date: Wed, 12 Feb 2025 06:54:19 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Herve Codina <herve.codina@...tlin.com>,
 Wolfram Sang <wsa+renesas@...g-engineering.com>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>
Cc: linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [RFC PATCH 3/3] i2c: i2c-core-of: Handle i2c bus extensions

On 05/02/2025 18:39, Herve Codina wrote:
>  
>  	dev_dbg(&adap->dev, "of_i2c: walking child nodes from %pOF\n", bus);
>  
> -	/* Register device directly attached to this bus */
> +	/*
> +	 * Register device directly described in this bus node before looking
> +	 * at extensions.
> +	 */
>  	for_each_available_child_of_node(bus, node) {
> +		/* Filter out extension node */
> +		if (of_node_name_eq(node, "i2c-bus-extension"))

Where is the ABI documented?

> +			continue;
> +
>  		if (of_node_test_and_set_flag(node, OF_POPULATED))
>  			continue;
>  
> @@ -103,6 +110,23 @@ static void of_i2c_register_children(struct i2c_adapter *adap,
>  			of_node_clear_flag(node, OF_POPULATED);
>  		}
>  	}
> +
> +	/* Look at extensions */
> +	for_each_available_child_of_node(bus, node) {
> +		if (!of_node_name_eq(node, "i2c-bus-extension"))
> +			continue;
> +
> +		extension = of_parse_phandle(node, "i2c-bus", 0);

And this?

> +		if (!extension)
> +			continue;
> +
Best regards,
Krzysztof