From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9919ACD3427 for ; Thu, 7 May 2026 10:38:35 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 99DE310E263; Thu, 7 May 2026 10:38:34 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="SSLrc/lN"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id 49B2C10EFBB for ; Thu, 7 May 2026 10:38:33 +0000 (UTC) Received: from killaraus.ideasonboard.com (2001-14ba-70f3-e800--a06.rev.dnainternet.fi [IPv6:2001:14ba:70f3:e800::a06]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id B7DFB664; Thu, 7 May 2026 12:38:27 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1778150307; bh=ydmTmsjfRJ0hth7ILhAiLaP0jMYvJoZgq1tSBlpEHq8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SSLrc/lNt577vc7KdRU5Lp7rvS19wjBj/Atp47wfhnbIQE29QoLJ9Z/c0K9jzOxMV P+0fOPK2eBeuitkxn2PxO76f2/ceMBkRx+EiwzLx0uHlfYzXQHv2INJ3XT+eJWAvEl 2ToegnWLEYNhE3g++h6115a5yHLIzBGuC3nZoonk= Date: Thu, 7 May 2026 13:38:30 +0300 From: Laurent Pinchart To: Biju Das Cc: "Lad, Prabhakar" , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Philipp Zabel , Geert Uytterhoeven , "magnus.damm" , "dri-devel@lists.freedesktop.org" , "linux-renesas-soc@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Fabrizio Castro , Tommaso Merciai , Prabhakar Mahadev Lad Subject: Re: [PATCH 1/4] dt-bindings: display: renesas,rzg2l-du: Add RZ/T2H and RZ/N2H support Message-ID: <20260507103830.GM1778786@killaraus.ideasonboard.com> References: <20260429170012.366537-1-prabhakar.mahadev-lad.rj@bp.renesas.com> <20260429170012.366537-2-prabhakar.mahadev-lad.rj@bp.renesas.com> <20260506195002.GA1778786@killaraus.ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, May 07, 2026 at 09:24:48AM +0000, Biju Das wrote: > On 06 May 2026 20:58, Lad, Prabhakar wrote: > > On Wed, May 6, 2026 at 8:50 PM Laurent Pinchart wrote: > > > On Wed, Apr 29, 2026 at 06:00:09PM +0100, Prabhakar wrote: > > > > From: Lad Prabhakar > > > > > > > > Document the Display Unit (DU) support for the RZ/T2H and RZ/N2H SoCs. > > > > > > > > The DU block on RZ/T2H is functionally equivalent to the RZ/G2UL DU > > > > and supports the DPI interface, but includes SoC-specific register differences. > > > > Add a dedicated compatible string to represent this variant. > > > > > > > > As the DU implementation on RZ/N2H matches RZ/T2H, describe it using > > > > an RZ/N2H specific compatible string with the RZ/T2H compatible as fallback. > > > > > > > > Unlike other DU variants which use a multi-port model, the RZ/T2H > > > > and RZ/N2H DU has a single output and is modelled using a single > > > > port node with one endpoint. Add a port property to support this and > > > > update the allOf constraints accordingly. > > > > > > Wouldn't it be simpler to always have a "ports" node, even for > > > variants with a single port ? > > > > > I agree that, from a binding perspective, always having a "ports" node keeps things simpler and > > consistent. Biju suggested this change based on earlier feedback for the RZ/G3E series. > > From G3E feedback, I got the impression that going forward all future SoCs needs to have > single port and multiple endpoints. That is the reason for suggesting port for new SoCs. Right, let's clarify that. TL;DR: it depends on the hardware architecture (what a surprise :-)) When reviewing the G3E, I noticed that the LCDC has a single output that is connected to one or multiple encoders, depending on the SoC. I think this should be modeled in DT with a single port. Note that this does not preclude using a "ports" node, containing a single "port@0". If you're confident enough that no future generation will require multiple ports, then it makes sense to standardize on a single "port" node and no "ports". If, on the other hand, you think that some SoCs would have multiple ports, then using a top-level "ports" node unconditionally would lead to simpler bindings. I'll let you all decide what you think is the most suitable approach. -- Regards, Laurent Pinchart