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 F333DFF885C for ; Sat, 25 Apr 2026 23:48:51 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F0DF610E203; Sat, 25 Apr 2026 23:48:50 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="aBosJ+CP"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7AC4110E4F3 for ; Sat, 25 Apr 2026 23:48:49 +0000 (UTC) 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-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" 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