From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6F23531C582 for ; Thu, 11 Sep 2025 15:48:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757605689; cv=none; b=d5Dr3/gtsq1W0h9M1NrqcioUgtE6PK0P7fmcHQ/boFrEdy9zF9w1eIEFwHW0OGERfTWC+grWkSxfdrE+kXONcGuOL8RQKPj21OCH588mB2C6dzsp9vA2yEX1229FWWJcwxkpPRKK+YPc34wIW+fnyl03FqZbRx8D5vKIXrIk6Bg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757605689; c=relaxed/simple; bh=JbWSkTYaAlcVdtB3PWKQ+Qyj4cVwJTcTQuAZQwKHNXU=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=jdEvTmSfqRZV+RRyR3NSyOU17hoKy6qDnI1ZI6jN9hZ6oiQ5tXEQRJg0CdNrr25yXzOG7m2EbB46HrBD0tH6lXTZWvKbOduZYgjO3xPVy0lAUPTTf7e4jY8BcBN5rTmPF/NygWqdxigiWwA+u7gUrAExsUE69SatKG9z6EJliHc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=0jQ8nyKP; arc=none smtp.client-ip=185.246.85.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="0jQ8nyKP" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id BBFE64E40C7A; Thu, 11 Sep 2025 15:48:05 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 8E4B460638; Thu, 11 Sep 2025 15:48:05 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 6101F102F2906; Thu, 11 Sep 2025 17:47:57 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1757605684; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:content-language:in-reply-to:references; bh=HdFDI1Zt4qmZyY2/ODcY5Tj0bjK1ieTRUu9lzaLuW8I=; b=0jQ8nyKPqSLy6yMyxtzn0i1pE7xvquZ56BuiAgAKXKI56Kd+C1wE64HxNKu3NabXnnnAsk qK5Aur62HdPoJgLNgsTqYG0YB92Dr14m8ByQZPFLBCigWw61XZsa1cQaeyFwipnB5z3Utm xw/AEbkf+sZVQ99MOc+AgTPll/rV+w4PncpZQ5RfsNtbQHwDkQGQ+nh9E163WTiJAdIPs9 3fUNHmWZ4NHqO7EekYXreubUIVJf6E/51JUh3v/gNoiOKqBQBpXtqX1/94WDxDmPw6Ymc3 H1bHa040x4bFCDI8+WGE/DsjN9CO6w05wfDENdPV/2FF/9psqmTuU91NNfdJyQ== Message-ID: <21f80397-be9c-49bd-b814-ea5f0eb5fdc8@bootlin.com> Date: Thu, 11 Sep 2025 17:47:57 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] drm/bridge: ite-it66121: Add drm_connector support From: Miguel Gazquez To: Dmitry Baryshkov Cc: Maxime Ripard , Phong LE , Neil Armstrong , Andrzej Hajda , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com, miquel.raynal@bootlin.com, kory.maincent@bootlin.com, romain.gantois@bootlin.com, praneeth@ti.com, Aradhya Bhatia References: <20250909-it66121-fix-v1-1-bc79ca83df17@bootlin.com> <6164422a-6265-4726-8da5-68bb8eafb9e6@bootlin.com> <20250911-innocent-daffodil-macaque-797f13@houat> <012046ab-d866-4b3a-8c8a-e130bc2b9628@bootlin.com> <2l5kp4ojrcsg2apcpv7mzeeypwynecyfesenks6zzvnst3qkbt@4yhbosy2zhah> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 Le 11/09/2025 à 17:40, Miguel Gazquez a écrit : > > > Le 11/09/2025 à 15:09, Dmitry Baryshkov a écrit : >> On Thu, Sep 11, 2025 at 02:49:59PM +0200, Miguel Gazquez wrote: >>> >>> >>> Le 11/09/2025 à 11:50, Maxime Ripard a écrit : >>>> On Thu, Sep 11, 2025 at 10:51:06AM +0200, Miguel Gazquez wrote: >>>>> >>>>> >>>>> Le 10/09/2025 à 04:28, Dmitry Baryshkov a écrit : >>>>>> On Tue, Sep 09, 2025 at 06:16:43PM +0200, Miguel Gazquez wrote: >>>>>>> From: Aradhya Bhatia >>>>>>> >>>>>>> Add support for DRM connector and make the driver support the older >>>>>>> format of attaching connectors onto the encoder->bridge->connector >>>>>>> chain. >>>>>>> This makes the driver compatible with display controller that only >>>>>>> supports the old format. >>>>>>> >>>>>>> [Miguel Gazquez: Rebased + made driver work with or without >>>>>>> DRM_BRIDGE_ATTACH_NO_CONNECTOR] >>>>>> >>>>>> What is the use case for not using DRM_BRIDGE_ATTACH_NO_CONNECTOR? >>>>> >>>>> Some display controller drivers (like the tilcdc) call >>>>> drm_bridge_attach >>>>> without DRM_BRIDGE_ATTACH_NO_CONNECTOR, so the bridge must support >>>>> both with >>>>> and without DRM_BRIDGE_ATTACH_NO_CONNECTOR to be compatible with >>>>> all display >>>>> controllers. >>>> >>>> I'd rather convert tilcdc to use DRM_BRIDGE_ATTACH_NO_CONNECTOR then. >>> >>> The problem is that doing that break devicetrees using the tilcdc and a >>> bridge who doesn't support DRM_BRIDGE_ATTACH_NO_CONNECTOR (there are >>> multiple bridges that don't support DRM_BRIDGE_ATTACH_NO_CONNECTOR), >>> and if >>> my understanding is correct breaking devicetrees is not allowed. >> >> How does it break devicetree? The drm_bridge_connector isn't a part of >> DT. > > > In the current situation, a board could have the tilcdc linked with a > bridge that does not support DRM_BRIDGE_ATTACH_NO_CONNECTOR (for > example, the analogix-anx6345) , and everything will work fine. > If we convert the tilcdc to always use DRM_BRIDGE_ATTACH_NO_CONNECTOR, > that same configuration will stop working. > > When I said "breaking devicetree" I meant that a devicetree describing > this setup would no longer produce a working system, not that the DT > files or bindings themselves are incorrect. > I didn't find any upstream dts with this configuration, but maybe there > is some out-of-tree dts which would be affected. > As far as I understand, we should avoid that. > If I can rephrase myself, is my understanding correct ? Do we care about breaking out-of-tree dts ? -- Miguel Gazquez, Bootlin Embedded Linux and Kernel engineering https://bootlin.com