linux-kernel - Re: [PATCH] media: i2c: thp7312: Don't require node availability

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Message-ID: <20250320142635.GA14394@pendragon.ideasonboard.com>
Date: Thu, 20 Mar 2025 16:26:35 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
	Paul Elder <paul.elder@...asonboard.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: i2c: thp7312: Don't require node availability

Hi Matti,

On Thu, Mar 20, 2025 at 10:35:35AM +0200, Matti Vaittinen wrote:
> It appears that the concept of available firmware nodes is not really
> applicable to the scenarios where a specific name is required from a
> node.
> 
> As explained[1] by Sakari:
> "OF only enumerates available nodes via the fwnode API, software nodes
> don't have the concept but on ACPI I guess you could have a difference
> in nodes where you have device sub-nodes that aren't available. Still,
> these ACPI device nodes don't have meaningful names in this context
> (they're 4-character object names) so you wouldn't use them like this
> anyway."
> 
> Use the fwnode_for_each_child_node() instead of the
> fwnode_for_each_available_child_node() In order to make it clearly
> visible that the 'availability' of the nodes does not need to be
> considered here.

Why not ? Node availability is a concept that exists in DT, and this
driver has only been tested on DT-based systems. Why can't we keep the
code as-is ?

> This will make it clearly visible that the code in
> this driver is suitable candidate to be converted to use the new
> fwnode_for_each_named_child_node()[2] when it gets merged.
> 
> [1]:
> https://lore.kernel.org/all/Z9rhfJUlCbi7kA2m@kekkonen.localdomain/
> [2]:
> https://lore.kernel.org/all/9c3880f74476436f39d796b5c10c540ae50b722c.1742225817.git.mazziesaccount@gmail.com/
> 
> Suggested-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Signed-off-by: Matti Vaittinen <mazziesaccount@...il.com>
> 
> ---
> NOTE: The change is compile tested only! Proper testing and reviewing is
> highly appreciated (as always).
> 
> ---
>  drivers/media/i2c/thp7312.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/thp7312.c b/drivers/media/i2c/thp7312.c
> index 8852c56431fe..4b66f64f8d65 100644
> --- a/drivers/media/i2c/thp7312.c
> +++ b/drivers/media/i2c/thp7312.c
> @@ -2067,7 +2067,7 @@ static int thp7312_parse_dt(struct thp7312_device *thp7312)
>  		return -EINVAL;
>  	}
>  
> -	fwnode_for_each_available_child_node(sensors, node) {
> +	fwnode_for_each_child_node(sensors, node) {
>  		if (fwnode_name_eq(node, "sensor")) {
>  			if (!thp7312_sensor_parse_dt(thp7312, node))
>  				num_sensors++;
> 
> base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6

-- 
Regards,

Laurent Pinchart