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 68025D41C12 for ; Thu, 11 Dec 2025 09:47:55 +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:References:From: To:Cc:Subject:Message-Id:Date:Content-Type:Content-Transfer-Encoding: Mime-Version:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=dEYtoHd6truLlW9dDvvW4TyZqvth1FwMIgnGkOwvmQk=; b=tjag+mi6HSWmCz5QHlsbyimx6p fF+Qyxr7ojbtS7vZGQEr73j5V2QKRnylV3XHFsz0kX1znMeHsdQVrFqSpxEy0HEW0WHghjm6BLmqn iWX3n9lb1uBTz2M6ncWXWgBeMJ9la87N0oDgR1EAi0CeduwdFn5njeXgNDxd5qOBA7etmtSGDd95j e4xsyxz+KWrapPf0qUjb9H8ejLmIh1FT+SQ5smpw73H24HMtCHUXCrP28kDzx7CRHXixasw7jAdYH 046JRG+GbYK8oMR2w8hru+0rIUjiOh3qylyk6WULJRmC65epet9epMaZuLqUULk+n1Zsrm8+32tYA ZD0W4rWg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTdH5-0000000GSLS-1Y3B; Thu, 11 Dec 2025 09:47:51 +0000 Received: from smtpout-03.galae.net ([185.246.85.4]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTdH1-0000000GSKt-1Rer for linux-arm-kernel@lists.infradead.org; Thu, 11 Dec 2025 09:47:50 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 29ACC4E41B6D; Thu, 11 Dec 2025 09:47:45 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id F16AA6068C; Thu, 11 Dec 2025 09:47:44 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 06BA9103C8C1E; Thu, 11 Dec 2025 10:47:39 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1765446463; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=dEYtoHd6truLlW9dDvvW4TyZqvth1FwMIgnGkOwvmQk=; b=RGSe8UYmgqic1d7gzrTAi6DwwYIydD58RU8J6fsmdoC5KlSEJclSPhwA9hemgK7p7TAyxb hLGOsvfjj0bVM4vks4oO+w20GsZOAkXbMLifL0QCJxE1oGW36lyEa36v4grMx2+PRF63ir inqrCx4Q+I9cc4QXro9EtuXKF14xvgVDPbE8BbAs4ykm46UbcLZCz0AIqjAdpU+rNGnW+5 0i4s2yiuKa/M8hfjtszF+uB89KxdDZiOmsrjUeeBMHPRyQWlww3fZvYT1Vhw7JTZII4k9P ML/tOQlh2X31xmjvB2bAR79Ojdv3x4BY0ox3b2l+56gDER59bOhtr2R0Lf9a3Q== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 11 Dec 2025 10:47:39 +0100 Message-Id: Subject: Re: [PATCH 03/21] drm/tilcdc: Remove simulate_vesa_sync flag Cc: "Jyri Sarha" , "Tomi Valkeinen" , "Maarten Lankhorst" , "Maxime Ripard" , "Thomas Zimmermann" , "David Airlie" , "Simona Vetter" , "Rob Herring" , "Krzysztof Kozlowski" , "Conor Dooley" , "Russell King" , "Bartosz Golaszewski" , "Tony Lindgren" , "Andrzej Hajda" , "Neil Armstrong" , "Robert Foss" , "Laurent Pinchart" , "Jonas Karlman" , "Jernej Skrabec" , "Markus Schneider-Pargmann" , "Louis Chauvet" , "Thomas Petazzoni" , "Miguel Gazquez" , , , , , To: "Kory Maincent" From: "Luca Ceresoli" X-Mailer: aerc 0.20.1 References: <20251126-feature_tilcdc-v1-0-49b9ef2e3aa0@bootlin.com> <20251126-feature_tilcdc-v1-3-49b9ef2e3aa0@bootlin.com> <20251211104024.1e7d5c42@kmaincent-XPS-13-7390> In-Reply-To: <20251211104024.1e7d5c42@kmaincent-XPS-13-7390> X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251211_014747_539911_75BF362C X-CRM114-Status: GOOD ( 23.49 ) 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 On Thu Dec 11, 2025 at 10:40 AM CET, Kory Maincent wrote: > On Wed, 10 Dec 2025 19:10:45 +0100 > "Luca Ceresoli" wrote: > >> Hi K=C3=B6ry, >> >> On Wed Nov 26, 2025 at 6:35 PM CET, Kory Maincent (TI.com) wrote: >> > The tilcdc hardware does not generate VESA-compliant sync signals. It >> > aligns the vertical sync (VS) on the second edge of the horizontal syn= c >> > (HS) instead of the first edge. To compensate for this hardware >> > behavior, the driver applies a timing adjustment in mode_fixup(). >> > >> > Previously, this adjustment was conditional based on the simulate_vesa= _sync >> > flag, which was only set when using external encoders. This appears >> > problematic because: >> > >> > 1. The timing adjustment seems needed for the hardware behavior regard= less >> > of whether an external encoder is used >> > 2. The external encoder infrastructure is driver-specific and being >> > removed due to design issues >> > 3. Boards using tilcdc without bridges (e.g., am335x-evm, am335x-evmsk= ) >> > may not be getting the necessary timing adjustments >> > >> > Remove the simulate_vesa_sync flag and apply the VESA sync timing >> > adjustment unconditionally, ensuring consistent behavior across all >> > configurations. While it's unclear if the previous conditional behavio= r >> > was causing actual issues, the unconditional adjustment better reflect= s >> > the hardware's characteristics. >> > >> > Signed-off-by: Kory Maincent (TI.com) >> > --- >> > >> > Only few board currently use tilcdc not associated to a bridge like th= e >> > am335x_evm or the am335x-evmsk. >> >> Have you tested this change on any affected board? >> >> The change looks good to me but without some testing it would be risky. > > I have tested it on few boards but not these mainline devicetree as I don= 't > have them. > > I have tested a tilcdc with tda998x bridge (BeagleBone Black), a tilcdc w= ith > ti,tilcdc,panel panel (BeagleBone with LCD cape), a tilcdc with it66121 b= ridge > (new Beagle Bone Green Eco board with HDMI cape). > That's all the boards I have. OK, thanks for the info. For future iterations, I think it's useful to mention, for all patches that may potentially break existing hardware, such info on which hardware you have tested. Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com