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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60146C04A68 for ; Thu, 28 Jul 2022 06:28:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233311AbiG1G20 (ORCPT ); Thu, 28 Jul 2022 02:28:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234225AbiG1G2W (ORCPT ); Thu, 28 Jul 2022 02:28:22 -0400 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8148E5E324; Wed, 27 Jul 2022 23:28:18 -0700 (PDT) Received: from [192.168.1.111] (91-158-154-79.elisa-laajakaista.fi [91.158.154.79]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id A18E96D4; Thu, 28 Jul 2022 08:28:15 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1658989696; bh=oCjtC3g82Ud1cVCYqkX2EY6KFanHwbRaoqifixuKbmA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pLx7l3bs6ZKtj6EfgHKRXHtx8LpDlK0WiczliWhXNIU0zM1CdjQ7hoY+McC3SApIU Whu8CwSs08TDg5lRIbdifPeFplGyXlkmPsQZJdkZjRG/R3JmWMXjPq8inSfSpjjL6e Fxjqm2fE0ttDKEKE912kE3ThBV7hLH7HR3TQt6OU= Message-ID: Date: Thu, 28 Jul 2022 09:28:12 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 1/8] dt-bindings: display: ti,am65x-dss: Add port properties for DSS Content-Language: en-US To: Nishanth Menon , Rob Herring Cc: Aradhya Bhatia , Jyri Sarha , David Airlie , Daniel Vetter , Krzysztof Kozlowski , Darren Etheridge , Vignesh Raghavendra , Rahul T R , Krunal Bhargav , Devarsh Thakkar , DRI Development List , Devicetree List , Linux Kernel List References: <20220719080845.22122-1-a-bhatia1@ti.com> <20220719080845.22122-2-a-bhatia1@ti.com> <20220720232845.GA4164694-robh@kernel.org> <20220722161621.p35apy5mstpgqhef@reverence> From: Tomi Valkeinen In-Reply-To: <20220722161621.p35apy5mstpgqhef@reverence> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/07/2022 19:16, Nishanth Menon wrote: > On 17:28-20220720, Rob Herring wrote: >>> On the bridge side R0->R2, G0->G1, B0->B2 would be tied to ground. >>> The bridge sees 24bits of data, but the lsb's are always zero. >> >> Unless the bridge ignores the LSBs, that's not the right way to do 16 to >> 24 bit. The LSBs should be connected to the MSB of the color component >> to get full color range. > > I unfortunately cannot point specifics without violating NDAs, so > will just give a broad perspective. > > Correct, this is not ideal, but in certain scenarios with limited > pins (due to iovoltage groups), we are indeed starting to see this > kind of usage model starting to pop up. Tradeoff is in a limit on > image quality, but that tends to be acceptable in certain lower cost > solutions. It doesn't require more pins. If the lowest bits are tied to ground the image is always a bit darker than it should, and you do not get the full brightness. But if you wire e.g. the red component: SoC : Bridge R2 -> R0 R3 -> R1 R4 -> R2 R0 -> R3 R1 -> R4 R2 -> R5 R3 -> R6 R4 -> R7 or R4 -> R0 R4 -> R1 R4 -> R2 R0 -> R3 R1 -> R4 R2 -> R5 R3 -> R6 R4 -> R7 You'll get the full range. Tomi