linux-kernel - Re: [PATCH v4 02/10] property: Add device_get_child_node_count

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Message-ID: <Z72Zp8tpnvlFGdQ_@smile.fi.intel.com>
Date: Tue, 25 Feb 2025 12:21:27 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc: Matti Vaittinen <mazziesaccount@...il.com>,
	Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
	Jonathan Cameron <jic23@...nel.org>,
	Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Daniel Scally <djrscally@...il.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Samuel Holland <samuel@...lland.org>,
	Hugo Villeneuve <hvilleneuve@...onoff.com>,
	Nuno Sa <nuno.sa@...log.com>, David Lechner <dlechner@...libre.com>,
	Javier Carrasco <javier.carrasco.cruz@...il.com>,
	Guillaume Stols <gstols@...libre.com>,
	Olivier Moysan <olivier.moysan@...s.st.com>,
	Dumitru Ceclan <mitrutzceclan@...il.com>,
	Trevor Gamblin <tgamblin@...libre.com>,
	Matteo Martelli <matteomartelli3@...il.com>,
	Alisa-Dariana Roman <alisadariana@...il.com>,
	Ramona Alexandra Nechita <ramona.nechita@...log.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH v4 02/10] property: Add
 device_get_child_node_count_named()

On Tue, Feb 25, 2025 at 11:40:16AM +0200, Heikki Krogerus wrote:
> > +/**
> > + * device_get_child_node_count_named - number of child nodes with given name
> > + *
> > + * Scan device's child nodes and find all the nodes with a specific name and
> > + * return the number of found nodes. Potential '@...ber' -ending for scanned
> > + * names is ignored. Eg,
> > + * device_get_child_node_count(dev, "channel");
> > + * would match all the nodes:
> > + * channel { }, channel@0 {}, channel@...bba {}...
> > + *
> > + * @dev: Device to count the child nodes for

This has an inconsistent kernel doc structure in comparison to the rest in this
file.

> > + * Return: the number of child nodes with a matching name for a given device.
> > + */
> > +unsigned int device_get_child_node_count_named(const struct device *dev,
> > +					       const char *name)
> > +{
> > +	struct fwnode_handle *child;
> > +	unsigned int count = 0;
> > +
> > +	device_for_each_child_node(dev, child)
> > +		if (fwnode_name_eq(child, "channel"))
> 
> s/"channel"/name/ ?
> 
> > +			count++;
> > +
> > +	return count;
> > +}
> > +EXPORT_SYMBOL_GPL(device_get_child_node_count_named);
> 
> I did not check how many users are you proposing for this, but if
> there's only one, then IMO this should not be a global function yet.
> It just feels to special case to me. But let's see what the others
> think.

The problem is that if somebody hides it, we might potentially see
a duplication in the future. So I _slightly_ prefer to publish and
then drop that after a few cycles if no users appear.

Also this misses the test cases.

-- 
With Best Regards,
Andy Shevchenko