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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 9AB7DCA9ED2 for ; Tue, 13 Oct 2026 11:12:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=AFHzR5TFeZGnqwFD0CxAvQ2lyL98rIjFKD+P/ODefPI=; b=uBsDv0m051uzz3aQfhcGeQFqqa I1NE05s4yYcyiEBZnWGnWgvFq+r0joUL5aIomIe6gm9ArtCbC3Rz7qPSwxjevv2EAa9xiEdct5767 6t6jKYHUNsDmBmgNVNicY5pPWUDtA6cLDMpzZsqGHOuCGo0Icd+QAL9qDuooz8bHA2FeT194Jipu8 bm2UMqtrqXMQrCujytc8d3cQGLmDec31KPX2Ip+1lIAE7Ubtkv0xQOc6MTzGhMcKGozq6wamuhFP9 c6wBtp6DrjzzH52UB7dWGj8MfuUxZU04YHRm3K+kHNdYtRUqjDcAKYSdqhEjvL6JRHEfwIBzVxOna SINBaJpQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xGaQd-0000000Cfss-21cG; Tue, 13 Oct 2026 11:12:19 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xGaQW-0000000CfsJ-12h3 for linux-arm-kernel@lists.infradead.org; Tue, 13 Oct 2026 11:12:18 +0000 Received: from killaraus.ideasonboard.com (unknown [185.104.138.147]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id C3259BC; Tue, 13 Oct 2026 13:10:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1791889807; bh=TLb9LXej9xG19WtKDwfE0UKEiJVXsGn15ErYlOXigNA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TlB8Bi30S5ri9HBtUHlzY6zY08CIHKtIIbBSKb5dt3zziN/pA8ByDTu5OVF15NSXn 4xX7plyX8+U+sKzluFZfMATxaCJc0e/z0jlrmKi5bA3n8XANXoMWrPozvIdfIiMT60 g+KdWAYoNwARwKCbEJ7Ue5TdERCKx0zSHWA4Wlas= Date: Tue, 13 Oct 2026 13:11:58 +0200 From: Laurent Pinchart To: Francesco Dolcini Cc: Leonardo Costa , Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Frank Li , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Leonardo Costa Subject: Re: [PATCH 0/3] Add VGA support for Apalis iMX6 Message-ID: <20261013111158.GG56180@killaraus.ideasonboard.com> References: <20261012-v1-apalis-imx6-enable-vga-v1-0-8905d8746504@toradex.com> <20261012164054.GA56180@killaraus.ideasonboard.com> <20261013090631.GA33628@francesco-nb> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261013090631.GA33628@francesco-nb> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261013_041217_878548_689D7651 X-CRM114-Status: GOOD ( 21.49 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Francesco, On Tue, Oct 13, 2026 at 11:06:31AM +0200, Francesco Dolcini wrote: > On Mon, Oct 12, 2026 at 06:40:54PM +0200, Laurent Pinchart wrote: > > On Mon, Oct 12, 2026 at 04:25:22AM -0300, Leonardo Costa wrote: > > > This series adds a device tree overlay that enables the VGA output on Apalis > > > iMX6, which is driven from a parallel RGB interface passing through a > > > non-programmable video DAC. > > > > > > The video DAC is a simple resistor network gated by an active-low > > > data-enable signal. For the bridge to work properly, this series also > > > changes the following in the dt-bindings and simple-bridge driver: > > > > > > - dt-bindings: Add a new compatible for the bridge in the simple-bridge > > > binding. This is necessary because the existing dumb-vga-dac compatible > > > doesn't describe a data-enable signal polarity. > > > > > > - simple-bridge: Add the VGA bridge match-table entry and timings > > > struct, setting the DRM_BUS_FLAG_DE_LOW flag for the bridge. > > > > Is there schematics available anywhere ? That would help reviewing the > > series ? > > This circuit is on the SoM, and the SoM schematics are > confidential and not generally available. > > I tried to extract as ascii art the relevant circuit, hope it helps Thank you, it makes things clearer. The circuit seems fairly generic. Wouldn't it be better to add an optional property ot the dumb-vga-dac instead of a new compatible string specific to Apalis ? > BLUE (5 bits) > ============= > DISP0_DATA[4] ---[R30 348R]---+ > DISP0_DATA[3] ---[R33 715R]---+ > DISP0_DATA[2] ---[R36 1.47K]---+-------- VGA1_B > DISP0_DATA[1] ---[R39 2.94K]---+ | > DISP0_DATA[0] ---[R42 5.90K]---+ D > | > DI0_PIN15 ------------------------------ G | T4 MMBF2201N > S > | > GND > > > RED (5 bits) > ============ > DISP0_DATA[15] --[R31 348R]---+ > DISP0_DATA[14] --[R34 715R]---+ > DISP0_DATA[13] --[R37 1.47K]---+-------- VGA1_R > DISP0_DATA[12] --[R40 2.94K]---+ | > DISP0_DATA[11] --[R43 5.90K]---+ D > | > DI0_PIN15 ------------------------------ G | T5 MMBF2201N > S > | > GND > > > GREEN (6 bits) > ============== > DISP0_DATA[10] --[R32 348R]---+ > DISP0_DATA[9] --[R35 715R]---+ > DISP0_DATA[8] --[R38 1.47K]---+ > DISP0_DATA[7] --[R41 2.94K]---+-------- VGA1_G > DISP0_DATA[6] --[R44 5.90K]---+ | > DISP0_DATA[5] --[R45 11.8K]---+ D > | > DI0_PIN15 ------------------------------ G | T6 MMBF2201N > S > | > GND -- Regards, Laurent Pinchart