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 7C225FF885C for ; Sat, 25 Apr 2026 23:49:05 +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: Content-Transfer-Encoding:Content-Type:MIME-Version:References: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=o6r2b2jMlnyEbHw3lQ5dPAKKOJP18qt0SqafBNS79kw=; b=ZaNTvZ2L+3UYu15YbTrFHA3Cg5 /evts78XRxwSCho+vGXjbxk0oJP5LCCcaibGyLHNABNgQYrfsPQ2CQGkhNwWK7fbg5cQWm7Us3XUX fZl6jF50e0DBbe89IvNwFNBhheruSC6oiolQpO5yVgW4i4XshfkF/dEGC7oIRKtiZ/mQNo2rWhtLm b+QtpsU36fIuyAOdYafmNIIoJ8WKuVL2BTRxXD+1r/HNGU7//F3kWtYgH3gdEfCCpI5/8Uh9SEI7o Zr6/c3Oca8IS1nXW3g9b2f2la1EJ3ecXndPP50uc8JPkc+vViGaUpCJuv82pX8P+dHCsuM628yRpW wa0evK1Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wGmk4-0000000F5H7-0iVD; Sat, 25 Apr 2026 23:48:56 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wGmk1-0000000F5Ge-1H61; Sat, 25 Apr 2026 23:48:54 +0000 Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id A956F1544; Sun, 26 Apr 2026 01:47:06 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1777160826; bh=Bp8RyEnQL0UxPw7eElHX5mckH3F8+ELKhrN2JVsixec=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aBosJ+CPRWpbzNhjnEakqNIWx8v6lvj20KVcTdhjJHN+Ndm/UNWPtYyXx6WQQbise L8hXN5SGvJ/awHLT9vgqFhYtYGLwhcvKW6IpH+xHcG2egbT8THwrLcbcNhFYgXfQdc j4ji2Tag7R41Gax3AEIZ/M90dRFcVrQECrMOoRD0= Date: Sun, 26 Apr 2026 02:48:45 +0300 From: Laurent Pinchart To: Dmitry Baryshkov Cc: Dennis Gilmore , Heiko Stuebner , Andrzej Hajda , Neil Armstrong , Robert Foss , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jonas Karlman , Jernej Skrabec , Maxime Ripard , Alexey Charkov , devicetree@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 3/6] drm/bridge: simple: Add the Lontium LT8711UXD DP-to-HDMI bridge Message-ID: <20260425234845.GC2964234@killaraus.ideasonboard.com> References: <20260425031011.2529364-1-dennis@ausil.us> <20260425031011.2529364-4-dennis@ausil.us> <20260425112844.GB2964234@killaraus.ideasonboard.com> <45evt7lkzuykoqsc2z27hsvm7fasmn6sr6gbjtdnme54jauehf@dmvon2o5emzd> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260425_164853_798352_D48A59F5 X-CRM114-Status: GOOD ( 38.33 ) 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 Sun, Apr 26, 2026 at 12:44:59AM +0300, Dmitry Baryshkov wrote: > On Sat, Apr 25, 2026 at 01:10:02PM -0500, Dennis Gilmore wrote: > > On Sat, Apr 25, 2026 at 9:24 AM Dmitry Baryshkov wrote: > > > On Sat, Apr 25, 2026 at 02:28:44PM +0300, Laurent Pinchart wrote: > > > > Hi Dennis, > > > > > > > > Thank you for the patch. > > > > > > > > On Fri, Apr 24, 2026 at 10:10:08PM -0500, Dennis Gilmore wrote: > > > > > The Lontium LT8711UXD is a high performance two lane Type-C/DP1.4 > > > > > to HDMI2.0 converter, designed to connect a USB Type-C source or > > > > > a DP1.4 source to an HDMI2.0 sink. > > > > > > > > As far as I can tell, the LT8711UXD has an I2C control interface. > > > > Shouldn't it be an I2C device ? > > > > > > From the datasheet: > > > > > > The device is capable of automatic operation which is > > > enabled by an integrated microprocessor that uses an > > > embedded SPI flash for firmware storage. System control > > > is also available through the use of a dedicated > > > configuration I2C slave interface. > > > > > > My guess was that it can either be an I2C device or it can function as a > > > simple platdev with no I2C controls. Please correct me if my > > > understanding was wrong. > > > > > > But now looking at the schematics, it seems to be connected to I2C6. > > > Which means that it should be desribed (and bound) as such. > > > > Hi Dmitry and Laurent, > > > > While the schematic shows that it can use I2C and has been wired up, > > it also shows that both MODE_SEL and I2C_ADDR have unpopulated 10k > > resistors; as a result, MODE_SEL is connected directly to GND, putting > > the bridge in autonomous mode. I confirmed this by running `i2cdetect > > -r -y 6`, with the only device on the bus being the HYM8563 RTC at > > 0x51. Without reworking the board, the device is not directly > > controllable and just runs autonomously. > > I think it would be nice to mention: > - In the commit for the bindings, that the device can be running > uncontrolled or it can be attached over I2C, bindings describe the > uncontrolled mode. > - In this commit message, the same. > - In the commit message for the board DT mention your findings about the > board, mention soldering R9 or R17 (which one?) and R27. Additionally, how are we going to handle boards where the device operates in I2C mode ? Will we use a different compatible string (maybe "lontium,lt8711uxd-i2c") ? If DT maintainers are fine with that, I have no objection to this patch. > > > > > Signed-off-by: Dennis Gilmore > > > > > Reviewed-by: Dmitry Baryshkov > > > > > --- > > > > > drivers/gpu/drm/bridge/simple-bridge.c | 5 +++++ > > > > > 1 file changed, 5 insertions(+) > > > > > > > > > > diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c > > > > > index 8aa31ca3c72d..42c1f3d5ba0c 100644 > > > > > --- a/drivers/gpu/drm/bridge/simple-bridge.c > > > > > +++ b/drivers/gpu/drm/bridge/simple-bridge.c > > > > > @@ -270,6 +270,11 @@ static const struct of_device_id simple_bridge_match[] = { > > > > > .data = &(const struct simple_bridge_info) { > > > > > .connector_type = DRM_MODE_CONNECTOR_HDMIA, > > > > > }, > > > > > + }, { > > > > > + .compatible = "lontium,lt8711uxd", > > > > > + .data = &(const struct simple_bridge_info) { > > > > > + .connector_type = DRM_MODE_CONNECTOR_HDMIA, > > > > > + }, > > > > > }, { > > > > > .compatible = "parade,ps185hdm", > > > > > .data = &(const struct simple_bridge_info) { -- Regards, Laurent Pinchart