linux-kernel - Re: [PATCH v2 2/6] ASoC: aoa: Use helper function for_each_child_of_node

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Message-ID: <8ad901c3-3fcb-4643-ac5a-c1f30f93d07f@csgroup.eu>
Date: Fri, 23 May 2025 12:51:43 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Ai Chao <aichao@...inos.cn>, perex@...ex.cz, tiwai@...e.com,
 johannes@...solutions.net, kuninori.morimoto.gx@...esas.com,
 lgirdwood@...il.com, broonie@...nel.org, jbrunet@...libre.com,
 neil.armstrong@...aro.org, khilman@...libre.com,
 martin.blumenstingl@...glemail.com, shengjiu.wang@...il.com,
 Xiubo.Lee@...il.com, festevam@...il.com, nicoleotsuka@...il.com,
 shawnguo@...nel.org, s.hauer@...gutronix.de, srinivas.kandagatla@...aro.org
Cc: linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org,
 linuxppc-dev@...ts.ozlabs.org, linux-renesas-soc@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-amlogic@...ts.infradead.org,
 imx@...ts.linux.dev, kernel@...gutronix.de, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 2/6] ASoC: aoa: Use helper function
 for_each_child_of_node_scoped()



Le 22/05/2025 à 07:02, Ai Chao a écrit :
> The for_each_child_of_node_scoped() helper provides a scope-based
> clean-up functionality to put the device_node automatically, and
> as such, there is no need to call of_node_put() directly.

I don't understand this explanation.

You say "no need to call of_node_put()" and the only thing you do in 
addition to changing from for_each_child_of_node() to 
for_each_child_of_node_scoped() is to _add_ a new call to of_node_put().

I would expect to see a _removal_ of some of_node_put() when I read your 
description.

Christophe

> 
> Thus, use this helper to simplify the code.
> 
> Signed-off-by: Ai Chao <aichao@...inos.cn>
> ---
>   sound/aoa/soundbus/i2sbus/core.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/aoa/soundbus/i2sbus/core.c b/sound/aoa/soundbus/i2sbus/core.c
> index ce84288168e4..20a4c5891afc 100644
> --- a/sound/aoa/soundbus/i2sbus/core.c
> +++ b/sound/aoa/soundbus/i2sbus/core.c
> @@ -207,6 +207,8 @@ static int i2sbus_add_dev(struct macio_dev *macio,
>   			}
>   		}
>   	}
> +	of_node_put(sound);
> +
>   	/* for the time being, until we can handle non-layout-id
>   	 * things in some fabric, refuse to attach if there is no
>   	 * layout-id property or we haven't been forced to attach.
> @@ -335,7 +337,6 @@ static int i2sbus_add_dev(struct macio_dev *macio,
>   
>   static int i2sbus_probe(struct macio_dev* dev, const struct of_device_id *match)
>   {
> -	struct device_node *np;
>   	int got = 0, err;
>   	struct i2sbus_control *control = NULL;
>   
> @@ -347,7 +348,7 @@ static int i2sbus_probe(struct macio_dev* dev, const struct of_device_id *match)
>   		return -ENODEV;
>   	}
>   
> -	for_each_child_of_node(dev->ofdev.dev.of_node, np) {
> +	for_each_child_of_node_scoped(dev->ofdev.dev.of_node, np) {
>   		if (of_device_is_compatible(np, "i2sbus") ||
>   		    of_device_is_compatible(np, "i2s-modem")) {
>   			got += i2sbus_add_dev(dev, control, np);