Re: [PATCH 1/2] arm64: dts: imx8mp-verdin: add dsi to hdmi functionality

From: Francesco Dolcini <francesco.dolcini@toradex.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Max Krummenacher <max.oss.09@gmail.com>,
	Max Krummenacher <max.krummenacher@toradex.com>,
	Fabio Estevam <festevam@gmail.com>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Marcel Ziswiler <marcel.ziswiler@toradex.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Philippe Schenker <philippe.schenker@toradex.com>,
	Rob Herring <robh+dt@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Shawn Guo <shawnguo@kernel.org>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64: dts: imx8mp-verdin: add dsi to hdmi functionality
Date: Fri, 2 Sep 2022 17:57:20 +0200	[thread overview]
Message-ID: <20220902155720.GB5699@francesco-nb.int.toradex.com> (raw)
In-Reply-To: <YxD09SqpcbB3dt8I@pendragon.ideasonboard.com>

Hello Laurent,
answering here for both patches (1/2 and 2/2).

On Thu, Sep 01, 2022 at 09:07:49PM +0300, Laurent Pinchart wrote:
> On Thu, Sep 01, 2022 at 05:40:50PM +0200, Max Krummenacher wrote:
> > From: Max Krummenacher <max.krummenacher@toradex.com>
> > 
> > Add the hdmi connector present on the dsi to hdmi adapter now
> > required by the upstream lontium bridge driver.
> > The dsi to hdmi adapter is enabled in an device tree overlay.
> 
> Shouldn't the connector also be in the overlay ? There's certainly no
> physical HDMI connector on the i.MX8MP Verdin SoM :-)

Toradex DTS include and overlay files structure so far has been a little
bit different and not following the expectation you just stated here,
you can just check the current *toradex*dts* files and you'll see that there
is other stuff that is not strictly part of the module.

Copying from a previous email thread on a very similar discussion [0]
some of the reasons:

 - The SoM dtsi representing not only the functionality implemented into
   the SoM, but the whole connector pinout to the carrier makes very easy
   to just include a different som.dtsi in the carrier board dts and just
   switch SoM, for example from a colibri-imx6 to a colibri-imx7.
 - We avoid code duplication

This is working for us pretty well so far and the majority of the users
of ours modules rely on this structure, we would prefer not to change that.

Francesco

[0] https://lore.kernel.org/all/20220413094449.GB118560@francesco-nb.int.toradex.com/

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