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Date: Fri, 1 Mar 2024 15:11:07 -0600
From: Rob Herring <robh@kernel.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Alexander Stein <alexander.stein@ew.tq-group.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>, linux-media@vger.kernel.org,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/3] media: dt-bindings: nxp,imx8-isi: Allow single port
 for single pipeline models
Message-ID: <20240301211107.GA3037358-robh@kernel.org>
References: <20240223140445.1885083-1-alexander.stein@ew.tq-group.com>
 <20240223140445.1885083-3-alexander.stein@ew.tq-group.com>
 <20240223141630.GA1313@pendragon.ideasonboard.com>
 <20240223141731.GB1313@pendragon.ideasonboard.com>
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In-Reply-To: <20240223141731.GB1313@pendragon.ideasonboard.com>

On Fri, Feb 23, 2024 at 04:17:31PM +0200, Laurent Pinchart wrote:
> On Fri, Feb 23, 2024 at 04:16:31PM +0200, Laurent Pinchart wrote:
> > Hi Alexander,
> > 
> > Thank you for the patch.
> > 
> > On Fri, Feb 23, 2024 at 03:04:44PM +0100, Alexander Stein wrote:
> > > In case the hardware only supports just one pipeline, allow using a
> > > single port node as well.
> > 
> > This is frowned upon in DT bindings, as it makes them more complicated
> > for little gain. The recommendation is to always use a ports node if a
> > device can have multiple ports for at least one of its compatibles.
> 
> And reading the cover letter, I see this causes warnings. I think we
> need guidance from Rob on this.

The warning is for:

ports {
  port@0 {};
};

It should/could be changed like this to fix it:

ports {
  port {};
};

But I've also said some warnings are guidance, not absolute. This is one 
of them. Some devices have optional port@1. In those cases, switching 
between 'port' and 'port@0' depending on 'port@1' makes little sense.

Rob