From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3ABD52E8E05 for ; Fri, 12 Sep 2025 10:28:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757672908; cv=none; b=nUKq/73Y9z4lyMqdRjvqbqqAEjYRqbrCDHZjeKoB8IqPO1VG/GOnbRgDGKewPUF7vPBeEzQqM+fXWXyWu/5HuZmjy2hb1dTdYMe5cntz5aU8PvL0bYEmAwpt7iw7KYcYvguSfLqW00UTZvZ49zb8BnfeQjqjPOjDSH/UFbI1kBQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757672908; c=relaxed/simple; bh=XHvzLANHb2pGo7ihBR6DIe9uzZw6cuzHHxU8rvOBtPI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uRMcY3u5vfIaOMR4xFagEgno/yUBJrYP7Z013ZnRS/gpy0pJL9Z/ocbQdQ/XAZx6acmzBSQM0Sjw2Pw6S0NtQfOfJ8Vrgg43UrcRJGANX/HnlnA7ngBZUunodjf/BtpoHwkB90TpKQtpPubRRl/SOFEMcdFKrHvQtU8dXKPYP08= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kjZ6ou1t; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kjZ6ou1t" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38229C4CEF1; Fri, 12 Sep 2025 10:28:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757672907; bh=XHvzLANHb2pGo7ihBR6DIe9uzZw6cuzHHxU8rvOBtPI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kjZ6ou1tv7rLaLTktshdDoPDpCPf1Lh/9rsEb2nWvUHx8btvCO9M91SQ/okITnPuM rfR1ZNmrQWqHG5C5JqK5pUge+KPh+OELNjJ7HkotzHgeH6uZNdABJDZNPhSzJLY3U9 D7bHiVsO/nYMSIBWgZ0TUKSYuoaJilMo2PPAv9YWOe5UJC9daf8W8LOemYn/2XDEbq sOFnRSju8/NQbdYcsoS+2M/5hb2kOVO+voD3QggvX2d/mDH6WqrZX30aATuphqkCcf U8VQepCjeCUWkhNbpuNY5+gw/bmSvl84SqPZyFZJooNORHvHnNDG5Pa7CLcqYCHLot 030QNhShgfwLw== Date: Fri, 12 Sep 2025 12:28:24 +0200 From: Maxime Ripard To: Miguel Gazquez Cc: Dmitry Baryshkov , 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 Subject: Re: [PATCH] drm/bridge: ite-it66121: Add drm_connector support Message-ID: <20250912-tricky-offbeat-cicada-e8bc2d@penduick> 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> <21f80397-be9c-49bd-b814-ea5f0eb5fdc8@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha384; protocol="application/pgp-signature"; boundary="b5r5hogjlsaahvlz" Content-Disposition: inline In-Reply-To: <21f80397-be9c-49bd-b814-ea5f0eb5fdc8@bootlin.com> --b5r5hogjlsaahvlz Content-Type: text/plain; protected-headers=v1; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH] drm/bridge: ite-it66121: Add drm_connector support MIME-Version: 1.0 On Thu, Sep 11, 2025 at 05:47:57PM +0200, Miguel Gazquez wrote: > Le 11/09/2025 =E0 17:40, Miguel Gazquez a =E9crit=A0: > > Le 11/09/2025 =E0 15:09, Dmitry Baryshkov a =E9crit=A0: > > > On Thu, Sep 11, 2025 at 02:49:59PM +0200, Miguel Gazquez wrote: > > > >=20 > > > >=20 > > > > Le 11/09/2025 =E0 11:50, Maxime Ripard a =E9crit=A0: > > > > > On Thu, Sep 11, 2025 at 10:51:06AM +0200, Miguel Gazquez wrote: > > > > > >=20 > > > > > >=20 > > > > > > Le 10/09/2025 =E0 04:28, Dmitry Baryshkov a =E9crit=A0: > > > > > > > On Tue, Sep 09, 2025 at 06:16:43PM +0200, Miguel Gazquez wrot= e: > > > > > > > > From: Aradhya Bhatia > > > > > > > >=20 > > > > > > > > Add support for DRM connector and make the driver support t= he older > > > > > > > > format of attaching connectors onto the encoder->bridge->co= nnector > > > > > > > > chain. > > > > > > > > This makes the driver compatible with display controller th= at only > > > > > > > > supports the old format. > > > > > > > >=20 > > > > > > > > [Miguel Gazquez: Rebased + made driver work with or without > > > > > > > > DRM_BRIDGE_ATTACH_NO_CONNECTOR] > > > > > > >=20 > > > > > > > What is the use case for not using DRM_BRIDGE_ATTACH_NO_CONNE= CTOR? > > > > > >=20 > > > > > > 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. > > > > >=20 > > > > > I'd rather convert tilcdc to use DRM_BRIDGE_ATTACH_NO_CONNECTOR t= hen. > > > >=20 > > > > The problem is that doing that break devicetrees using the tilcdc a= nd 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. > > >=20 > > > How does it break devicetree? The drm_bridge_connector isn't a part of > > > DT. > >=20 > >=20 > > 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. > >=20 > > 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. > >=20 >=20 > If I can rephrase myself, is my understanding correct ? Do we care about > breaking out-of-tree dts ? There's only so much we can do, and we can't fix issues we can't know about. So no. Maxime --b5r5hogjlsaahvlz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iJUEABMJAB0WIQTkHFbLp4ejekA/qfgnX84Zoj2+dgUCaMP1xwAKCRAnX84Zoj2+ dvFUAX4mGzr+jhCS+JMrw0EOA1ttiPb9P5MJpffpYl0eKwA4c4dvT4RoSwj4aDWd GZko+C8BfR0tqqWniPbxIPbfBsehe8DQq1xZlq4pHBwpQPK+C7IJWwfhSBcMrpuI ljCJs6Dseg== =J7wq -----END PGP SIGNATURE----- --b5r5hogjlsaahvlz--