From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B7BB34B95C0; Tue, 13 Oct 2026 11:12:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791889933; cv=none; b=tn7i6PvHauuaYV1uTeOvC9EZZ1U9jIl8BHCkCFPeFDUepyx4gMhjSb0mqymEjLs2a0mLyOp2faHHN4xdtQGry3DT/T6qkR2VXjGwX0Mz79zAmChJQvt4ly2VRAlnE8CaSAhajb9SVoMrxGijzZZkH1SOy7+6GsUQOOwBOxf0AaE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791889933; c=relaxed/simple; bh=TLb9LXej9xG19WtKDwfE0UKEiJVXsGn15ErYlOXigNA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fEzSpnaNJq6FTNWKtflsGk6qB8mjLkAkZUAWnTbckYo+o/xJ02+JsuxIiFiGF1lnmD9RBTIotsAOvwv8b5bP85KXO8vyyvu1E/pE3ONH3W4wDgvbGXstzuyuS41w4xnbhVTzZ6+g9LiBbAjuGgj01dM/956R61UC43Q+qQfoYco= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=TlB8Bi30; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="TlB8Bi30" 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> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261013090631.GA33628@francesco-nb> 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