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 0597FD41C14 for ; Thu, 11 Dec 2025 09:40:46 +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:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WZVCcNfKSTt2Hd14gUawnCXPs39wl8U5m2GxT9YHICY=; b=F3R2EeJKF3XiC6TuXND462FTNH jcoU8QEnF+hqZJyIXuQQkhowSoYZAz+6ebbXevIZJU6JzXVGIb6nyc42+7sLPxIouLhRt0ibkhC+Z rc/IzPmwTfBTmdgqn7SNvXXLFf2Qi304I+CrMOd6yPfjqGJbDZeBRus5yTBI6+g230Qn50vImbm/D FsjPVeXtT7Yz9hNdx+j+mYlrWo/2+qJRJCyQXifLn7NZZ7tyP8oAIBy9x2Ycnt3qdXITfgDEyOy8J ZpIlq7o3Y3p6X29S9gybpIUB4wvvoyhelTuNzttgT838hy1FtY4RaGDr4YeGWrq8fC2AHg4RwZyGY uGBVooDA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTdAA-0000000GRuV-3lFE; Thu, 11 Dec 2025 09:40:42 +0000 Received: from smtpout-02.galae.net ([185.246.84.56]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTdA6-0000000GRtg-3gXE for linux-arm-kernel@lists.infradead.org; Thu, 11 Dec 2025 09:40:41 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 17EB01A20DF; Thu, 11 Dec 2025 09:40:34 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id DF0096068C; Thu, 11 Dec 2025 09:40:33 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 14F2B103C8D53; Thu, 11 Dec 2025 10:40:25 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1765446032; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=WZVCcNfKSTt2Hd14gUawnCXPs39wl8U5m2GxT9YHICY=; b=N8BY+0RW1/KCWSmz1ejzT8wkU32hMHoROWuSW1FXKVX56lJPTLnrOG87aYRBJX3eLmwdQz ElonbiZKTB2yohpJE+9k8TDVw2t9dMGuu4ov3c9BVvflGTXLZViwe/G9lROCs1KMjA5Cg1 HqAOW3glYucmbg2jWQCfC+vmSqV0f3bRAfIGwFYLKzsrZIZn5PifwpK4SdhZWFCK8zSDep NJinbhnm5mFm/zI9m2xrgrfv6TFXNgAyWJZmSCZG+MROAk2te2haBPin+EoimEwAAmRl4c 665fBJnGyGTn7KpP/dBIwnBN6Ey1VxFEPONWoRQP8/KCoFPe22GeYDOR7es8FA== Date: Thu, 11 Dec 2025 10:40:24 +0100 From: Kory Maincent To: "Luca Ceresoli" 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" , , , , , Subject: Re: [PATCH 03/21] drm/tilcdc: Remove simulate_vesa_sync flag Message-ID: <20251211104024.1e7d5c42@kmaincent-XPS-13-7390> In-Reply-To: References: <20251126-feature_tilcdc-v1-0-49b9ef2e3aa0@bootlin.com> <20251126-feature_tilcdc-v1-3-49b9ef2e3aa0@bootlin.com> Organization: bootlin X-Mailer: Claws Mail 4.2.0 (GTK 3.24.41; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251211_014039_074590_F146CF48 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 On Wed, 10 Dec 2025 19:10:45 +0100 "Luca Ceresoli" wrote: > Hi K=C3=B6ry, >=20 > 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 sync > > (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 regardl= ess > > 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 behavior > > was causing actual issues, the unconditional adjustment better reflects > > the hardware's characteristics. > > > > Signed-off-by: Kory Maincent (TI.com) > > --- > > > > Only few board currently use tilcdc not associated to a bridge like the > > am335x_evm or the am335x-evmsk. =20 >=20 > Have you tested this change on any affected board? >=20 > 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 with ti,tilcdc,panel panel (BeagleBone with LCD cape), a tilcdc with it66121 bri= dge (new Beagle Bone Green Eco board with HDMI cape). That's all the boards I have. Regards, --=20 K=C3=B6ry Maincent, Bootlin Embedded Linux and kernel engineering https://bootlin.com