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 2DCFCD3E76A for ; Wed, 10 Dec 2025 18:11:11 +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=zHScQ9epIs7tSkBpcNfLT2ySqJpIcU3hl0yiRWEMSxU=; b=yds5cs7f14F/QzCDunk6KMHWpD zszgMncjm1u+JWZt1umwOW7JR/vYz8jKvC2KceZPiIywhPi7++YKu7xbMEzvoWrJLgNB/b5rfQfvr q5Xi6yimmKSeIHoIRpqte2eEGO3msz+VujQD9JFXiugXpdP6a64z/a8DoMReHLIR582y9ZLJi8zwi vc7VqXA4KCBHBKvqGMfm5p1um2QBWIl5vHwJSFYsyzUg/h3Pd/oWHvb+Wg6iJjONBI4v+7hU4Wr5x VDOkghF7LPcD1VfSeJ2h6fRWlY75u3RdVUsH7S3cxLfiuYoPoHFhUlofYoMhYNtMk3eIYfjoyCDmZ JOwnCMGg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vTOeU-0000000FjSE-1rG7; Wed, 10 Dec 2025 18:11:04 +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 1vTOeR-0000000FjRf-2DfH for linux-arm-kernel@lists.infradead.org; Wed, 10 Dec 2025 18:11:01 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 4A4FD4E41B4E; Wed, 10 Dec 2025 18:10:56 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id D59F760714; Wed, 10 Dec 2025 18:10:55 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 63FF8103C8CB3; Wed, 10 Dec 2025 19:10:46 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1765390254; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=zHScQ9epIs7tSkBpcNfLT2ySqJpIcU3hl0yiRWEMSxU=; b=O6jczRAHlyE369TuBgKbSoI5sr+D8r2p/p/jJJNzLR9kXxPqm7i8xrI7fQB90odCyPIXe1 4YZEYdjGPIrzpd27WpJ88/6qed4b09CpY+O8jxnssomse8LoTt8CSvaA6wr3dlSpRtijCJ vAHmY6R0ZD1eQUyUZarC66Ne+Ux/2RcQd5t77tAyFL1OfRlXrUkmm1ZMn+BPB5r7RdTl7h Qk+hr7+AYIIFJwhZj0Tgwd+BKfz6bdCRIMotppabJdlVf4Bs8C4uOdOKVnpS/5nLW/u5hk /fANJbwQ2wd/+NdKjXBdlPyCrER7pQDgNesMJqkCFPh9spNiUJ1olbTsiUR65A== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 10 Dec 2025 19:10:45 +0100 Message-Id: Subject: Re: [PATCH 03/21] drm/tilcdc: Remove simulate_vesa_sync flag Cc: "Markus Schneider-Pargmann" , "Louis Chauvet" , "Thomas Petazzoni" , "Miguel Gazquez" , , , , , To: "Kory Maincent (TI.com)" , "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" 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> In-Reply-To: <20251126-feature_tilcdc-v1-3-49b9ef2e3aa0@bootlin.com> X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251210_101059_704499_8ABD2484 X-CRM114-Status: GOOD ( 14.41 ) 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 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 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_sy= nc > flag, which was only set when using external encoders. This appears > problematic because: > > 1. The timing adjustment seems needed for the hardware behavior regardles= s > 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. Have you tested this change on any affected board? The change looks good to me but without some testing it would be risky. Luca -- Luca Ceresoli, Bootlin Embedded Linux and Kernel engineering https://bootlin.com