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Date: Tue, 17 Jun 2025 15:11:52 +0200
From: Danilo Krummrich <dakr@kernel.org>
To: Rob Herring <robh@kernel.org>
Cc: Remo Senekowitsch <remo@buenzli.dev>,
	Saravana Kannan <saravanak@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Miguel Ojeda <ojeda@kernel.org>,
	Alex Gaynor <alex.gaynor@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
	Benno Lossin <lossin@kernel.org>,
	Andreas Hindborg <a.hindborg@kernel.org>,
	Alice Ryhl <aliceryhl@google.com>, Trevor Gross <tmgross@umich.edu>,
	Mark Brown <broonie@kernel.org>,
	Dirk Behme <dirk.behme@de.bosch.com>, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org
Subject: Re: [PATCH v1 3/3] samples: rust: platform: Add property child and
 reference args examples
Message-ID: <aFFpmKLKR2hGs1I1@pollux>
References: <20250616154511.1862909-1-remo@buenzli.dev>
 <20250616154511.1862909-4-remo@buenzli.dev>
 <CAL_JsqKXrsdGjTE5KDkqmVHUK5urMJnWSLWgEi8H1yM21gcOCA@mail.gmail.com>
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In-Reply-To: <CAL_JsqKXrsdGjTE5KDkqmVHUK5urMJnWSLWgEi8H1yM21gcOCA@mail.gmail.com>

On Tue, Jun 17, 2025 at 08:01:08AM -0500, Rob Herring wrote:
> On Mon, Jun 16, 2025 at 10:45 AM Remo Senekowitsch <remo@buenzli.dev> wrote:
> > @@ -91,6 +95,13 @@ fn properties_parse(dev: &device::Device) -> Result {
> >          let prop: KVec<i16> = fwnode.property_read_array_vec(name, 4)?.required_by(dev)?;
> >          dev_info!(dev, "'{name}'='{prop:?}' (KVec)\n");
> >
> > +        for child in fwnode.children() {
> > +            let name = c_str!("test,ref-arg");
> > +            let nargs = NArgs::N(2);
> > +            let prop: FwNodeReferenceArgs = child.property_get_reference_args(name, nargs, 0)?;
> 
> Is there some reason we can just pass 2 in rather than nargs? Seems
> overly verbose for my tastes.

It's because you could also pass NArgs::Prop("foo-bar") to indicate the the
name of the property telling the number of arguments.

NArgs is defined as

	pub enum NArgs<'a> {
	    /// The name of the property of the reference indicating the number of
	    /// arguments.
	    Prop(&'a CStr),
	    /// The known number of arguments.
	    N(u32),
	}

and FwNode::property_get_reference_args() can match against the corresponding
enum variant to cover both cases.

> > +            dev_info!(dev, "'{name}'='{prop:?}'\n");
> > +        }
> > +
> >          Ok(())
> >      }
> >  }
> > --
> > 2.49.0
> >