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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 B0F6DF419B9 for ; Wed, 15 Apr 2026 13:51:22 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 05B7D10E1EA; Wed, 15 Apr 2026 13:51:22 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ew.tq-group.com header.i=@ew.tq-group.com header.b="VSRIQxVA"; dkim-atps=neutral Received: from www537.your-server.de (www537.your-server.de [188.40.3.216]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3643F10E6E0 for ; Wed, 15 Apr 2026 13:51:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=ew.tq-group.com; s=default2602; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=lhottTYc7RM1jdLqnyonzT5k/dg3DnW974HgNK0Q368=; b=VSRIQxVA2pT1LTIND1TMdSWd80 ic6mtIRWFAj5GY4vG412A2Q7V8ELw8+w6A4EarnxgZFBy+vXpO4YOs4AcdDbTGKmS1yuIh+x7ueoQ AeD4aDl3Hz6an8CXI4LdkClsyqdjJIjDvW5nU4HY0sQCmiVkBc1j+Lot/SWUM/Ig1xJ5FcTU3BpDq q9AsIYAnD/Y52SedKPvlfiTzxXXQYhsiCSdcEwaK0f3bDpkWQg53bh3XyYzeUg/kegWRC8dWdLfhX 5VGaCKVq6K9AaM0jy+pZ+7KXAXis3xUqxRL4Z5t6zSbh4oj/G1LiAoaE8OC0dDPIUz/XKNrIqM3XK IU0UAxng==; Received: from sslproxy08.your-server.de ([78.47.166.52]) by www537.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1wD0eB-000B8k-1X; Wed, 15 Apr 2026 15:51:15 +0200 Received: from localhost ([127.0.0.1]) by sslproxy08.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1wD0eA-000OuZ-05; Wed, 15 Apr 2026 15:51:14 +0200 From: Alexander Stein To: andrzej.hajda@intel.com, neil.armstrong@linaro.org, rfoss@kernel.org, Sudarshan Shetty Cc: Laurent.pinchart@ideasonboard.com, jonas@kwiboo.se, jernej.skrabec@gmail.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, marex@denx.de, valentin@compulab.co.il, luca.ceresoli@bootlin.com, philippe.schenker@toradex.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Sudarshan Shetty Subject: Re: [PATCH v3 1/1] drm: bridge: ti-sn65dsi83: Fix DSI mode flags for stable LVDS output Date: Wed, 15 Apr 2026 15:51:13 +0200 Message-ID: <6721341.e9J7NaK4W3@steina-w> Organization: TQ-Systems GmbH In-Reply-To: <20260412053811.662461-2-tessolveupstream@gmail.com> References: <20260412053811.662461-1-tessolveupstream@gmail.com> <20260412053811.662461-2-tessolveupstream@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" X-Virus-Scanned: Clear (ClamAV 1.4.3/27972/Wed Apr 15 08:24:27 2026) X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Am Sonntag, 12. April 2026, 07:38:11 CEST schrieb Sudarshan Shetty: > The current DSI mode configuration enables VIDEO_BURST and disables > horizontal front porch (HFP) and back porch (HBP) transmission using > MIPI_DSI_MODE_VIDEO_NO_HFP and MIPI_DSI_MODE_VIDEO_NO_HBP. >=20 > However, the SN65DSI83/84 bridge relies on receiving full horizontal > timing information over DSI in order to correctly reconstruct the LVDS > output timings. When HFP and HBP are not transmitted, the bridge cannot > recreate the required timing parameters, resulting in unstable or > missing display output on some panels. >=20 > Additionally, while burst mode is supported by the hardware, its use > depends on continuous clock behavior from the DSI host. In practice, > burst mode may introduce instability depending on the host controller > implementation, as the DSI link may transition to low-power state > between bursts. >=20 > In testing, removing burst mode and ensuring full horizontal timing > transmission results in stable LVDS output across affected panels. >=20 > Update the DSI mode flags to: > - Drop MIPI_DSI_MODE_VIDEO_BURST > - Drop MIPI_DSI_MODE_VIDEO_NO_HFP > - Drop MIPI_DSI_MODE_VIDEO_NO_HBP >=20 > This aligns with common system configurations where non-burst mode is > preferred and full timing information is transmitted over DSI. >=20 > Signed-off-by: Sudarshan Shetty Tested-by: Alexander Stein # imx8mq, imx8m= m, imx8mm on both tm070jvhg33 and g133han01 displays. Best regards Alexander > --- > drivers/gpu/drm/bridge/ti-sn65dsi83.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) >=20 > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/brid= ge/ti-sn65dsi83.c > index fef6bca3273f..9d51dc2b75bc 100644 > --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c > @@ -976,9 +976,8 @@ static int sn65dsi83_host_attach(struct sn65dsi83 *ct= x) > =20 > dsi->lanes =3D dsi_lanes; > dsi->format =3D MIPI_DSI_FMT_RGB888; > - dsi->mode_flags =3D MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | > - MIPI_DSI_MODE_VIDEO_NO_HFP | MIPI_DSI_MODE_VIDEO_NO_HBP | > - MIPI_DSI_MODE_VIDEO_NO_HSA | MIPI_DSI_MODE_NO_EOT_PACKET; > + dsi->mode_flags =3D MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_NO_HSA | > + MIPI_DSI_MODE_NO_EOT_PACKET; > =20 > ret =3D devm_mipi_dsi_attach(dev, dsi); > if (ret < 0) { >=20 =2D-=20 TQ-Systems GmbH | M=FChlstra=DFe 2, Gut Delling | 82229 Seefeld, Germany Amtsgericht M=FCnchen, HRB 105018 Gesch=E4ftsf=FChrer: Detlef Schneider, R=FCdiger Stahl, Stefan Schneider http://www.tq-group.com/