linux-kernel - Re: [PATCH v2 04/16] ACPI: property: Return present device nodes only on fwnode interface

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Message-ID: <20250924095725.GD28073@pendragon.ideasonboard.com>
Date: Wed, 24 Sep 2025 12:57:25 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-input@...r.kernel.org, linux-leds@...r.kernel.org,
	linux-media@...r.kernel.org, netdev@...r.kernel.org,
	linux-spi@...r.kernel.org, "Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Daniel Scally <djrscally@...il.com>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Javier Carrasco <javier.carrasco@...fvision.net>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
	Matthias Fend <matthias.fend@...end.at>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Paul Elder <paul.elder@...asonboard.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Horatiu Vultur <horatiu.vultur@...rochip.com>,
	UNGLinuxDriver@...rochip.com, Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Mark Brown <broonie@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH v2 04/16] ACPI: property: Return present device nodes
 only on fwnode interface

On Wed, Sep 24, 2025 at 10:45:50AM +0300, Sakari Ailus wrote:
> fwnode_graph_get_next_subnode() may return fwnode backed by ACPI device
> nodes and there has been no check these devices are present in the system,
> unlike there has been on fwnode OF backend. In order to provide consistent
> behaviour towards callers, add a check for device presence by introducing
> a new function acpi_get_next_present_subnode(), used as the
> get_next_child_node() fwnode operation that also checks device node
> presence.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> ---
>  drivers/acpi/property.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> index 5438592dc136..01f3880ffcce 100644
> --- a/drivers/acpi/property.c
> +++ b/drivers/acpi/property.c
> @@ -1319,6 +1319,26 @@ acpi_get_next_subnode(const struct fwnode_handle *fwnode,
>  	return NULL;
>  }
>  
> +/**

/*

as the function is static ?

> + * acpi_get_next_present_subnode - Return the next present child node handle for a fwnode
> + * @fwnode: Firmware node to find the next child node for.
> + * @child: Handle to one of the device's child nodes or a null handle.

A blank line here would be nice.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>

> + * Like acpi_get_next_subnode(), but the device nodes returned by
> + * acpi_get_next_present_subnode() are guaranteed to be present.
> + * Returns: The next sub-node fwnode handle.
> + */
> +static struct fwnode_handle *
> +acpi_get_next_present_subnode(const struct fwnode_handle *fwnode,
> +			      struct fwnode_handle *child)
> +{
> +	do {
> +		child = acpi_get_next_subnode(fwnode, child);
> +	} while (is_acpi_device_node(child) &&
> +		 !acpi_device_is_present(to_acpi_device_node(child)));
> +
> +	return child;
> +}
> +
>  /**
>   * acpi_node_get_parent - Return parent fwnode of this fwnode
>   * @fwnode: Firmware node whose parent to get
> @@ -1664,7 +1684,7 @@ static int acpi_fwnode_irq_get(const struct fwnode_handle *fwnode,
>  		.property_read_string_array =				\
>  			acpi_fwnode_property_read_string_array,		\
>  		.get_parent = acpi_node_get_parent,			\
> -		.get_next_child_node = acpi_get_next_subnode,		\
> +		.get_next_child_node = acpi_get_next_present_subnode,	\
>  		.get_named_child_node = acpi_fwnode_get_named_child_node, \
>  		.get_name = acpi_fwnode_get_name,			\
>  		.get_name_prefix = acpi_fwnode_get_name_prefix,		\

-- 
Regards,

Laurent Pinchart