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 244B724DD09; Wed, 3 Dec 2025 08:30:49 +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=1764750650; cv=none; b=Ux2cUXs7gf19vnS91uXFDNQA++r4cgG+NCZTjfyrDvuP8C7Cs5T+6lWpBwMwIN7Dy0DUW5DD9FRt+2OAHju/1yItlX2jc5B/uZdZY7FCAj/SbbbHRNE2XR0uH3Ya2wAhtU0W/WNsSh84qfiUgucUgKl4x2OELhiZINSppyTdWQI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764750650; c=relaxed/simple; bh=zyF/r0fjZEG5Zc5d3W/4Gh2VeH+el4jv7LMS1PSNlk0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=h6GaE7S/GvVczqt/+09XZIObUBzAufNHDgwbaz49MoRGpJpcPZ5WYFzeqss05QrKXa0YWPGnl60JPPxkfSSAg+cC+lNjUBykQggQa7Rgf0aSAtn6yPaNWzo1h2/cxx+M5HpHm2JP14hR8j3nOt41W3KpGHbEMkXS/9SfUZeYNaI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rI6h+xJT; 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="rI6h+xJT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A3A9C4CEFB; Wed, 3 Dec 2025 08:30:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764750649; bh=zyF/r0fjZEG5Zc5d3W/4Gh2VeH+el4jv7LMS1PSNlk0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rI6h+xJTutYGBiCMHFSC/CvZ/aY8wz+s4/Zl+p2h9DrLvfIzTqd/+d1iR4lErm5FB mKQKFs37QSydLBwjhKPPZwTcCewwu9vwRaOKnDWzWiD0YAwKFCKAInPN20z5mmD7fn tl8JtUqV3tiQsXc5zFT8Hi5EDUYl36G54aqvYte5xk6qTXQFkpq65iRsQ3o4WGXNtN NCklPbkMxcfeLXearae5GTpSabNxYuf8ZOvHtVMKnxs1TQBgmIVeiWSG0BEA1a5KDf abjPoyZNTSRel49GIShJu3LoR1+/e6jpovfKAlDCHifWa8lAhlupOrLbemnC5nh4e/ TGmHTfIEDA8gw== Date: Wed, 3 Dec 2025 09:30:47 +0100 From: Krzysztof Kozlowski To: Kory Maincent Cc: Tomi Valkeinen , Markus Schneider-Pargmann , Luca Ceresoli , Louis Chauvet , Thomas Petazzoni , Miguel Gazquez , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, Jyri Sarha , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Russell King , Bartosz Golaszewski , Tony Lindgren , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec Subject: Re: [PATCH 05/21] ARM: dts: omap: Bind panel to panel-dpi instead of ti,tilcdc,panel driver Message-ID: <20251203-aromatic-heavy-loon-0cbd14@quoll> References: <20251126-feature_tilcdc-v1-5-49b9ef2e3aa0@bootlin.com> <96b1b7bf-ddbe-4213-a201-dc89cf2998dd@ideasonboard.com> <3bc5bf92-05c3-4841-ab28-9bab2bb31cd5@kernel.org> <20251202104244.59a9e83d@kmaincent-XPS-13-7390> <20251202114416.09624a4b@kmaincent-XPS-13-7390> <94e254fa-289d-41ed-909f-1742cfbb2690@kernel.org> <20251202121856.0da62885@kmaincent-XPS-13-7390> <1d9a9269-bfda-4d43-938b-2df6b82b9369@ideasonboard.com> <20251202135605.053ada96@kmaincent-XPS-13-7390> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251202135605.053ada96@kmaincent-XPS-13-7390> On Tue, Dec 02, 2025 at 01:56:05PM +0100, Kory Maincent wrote: > On Tue, 2 Dec 2025 13:51:59 +0200 > Tomi Valkeinen wrote: > > > Hi Kory, > > > > On 02/12/2025 13:18, Kory Maincent wrote: > > > On Tue, 2 Dec 2025 11:47:40 +0100 > > > Krzysztof Kozlowski wrote: > > > I will not NAK, removing bindings and breaking users is under some > > conditions acceptable. You just need to come with the reasons and impact. > > > > Reason "is ugly" is usually not good enough. Especially if things were > > working. > > Thanks for you reply. > > > >> > > >> DTS cannot go to drm, which means you either need to separate the change > > >> and make entire work bisectable and backwards compatible for some time > > >> OR at least document clearly the impact as we always ask. > > > > > > The thing is, if I split it, it has to be in 3. One for the of DRM bus flags > > > support, a second for the the devicetree and binding change and a third for > > > the whole tilcdc and tda998x cleaning stuff. I think I will go for one > > > series, with better documentation. > > > > > > Now, what is your point of view on my question. Will you nak any binding > > > removal even if the binding is ugly and legacy and imply maintaining an > > > non-standard tilcdc panel driver? I know it breaks DTB compatibility but > > > there is several argument to not keep it. See patch 6. > > The binding being ugly and having to maintain non-standard tilcdc panel > > driver may be nice things for us, the users don't care. The users care > > if their board no longer works. > > Yes I understand but then I have another question. At what cost should we > continue to support legacy binding? That's mostly question to platform maintainers and users. Extrapolating kernel rule - we never break the user-space - we never break the users, thus we take significant cost. And that significant cost can be the cost of making the transition smooth or smoother. > > Just figured out this case already happened, ti,tilcdc,slave binding was > removed from the tilcdc driver: > 739acd85ffdb7 ("drm/tilcdc: Remove obsolete "ti,tilcdc,slave" dts binding > support") > > Even if there is still one mainline device tree that uses it: > am335x-base0033.dts. :/ If that commit broke existing users, it is a good argument for your changes, but you need to explicitly use that argument in commit msg. > > > And how does this sync with u-boot? It also has code for at least for a > > few of these boards. > > U-boot has indeed a driver for the ti,tilcdc,panel binding. > Changing this devicetree would beak display for these board in U-boot as it > currently does not support the "panel-dpi" binding. Thanks for checking, regardless of decision this also should be in commit msg. Maybe things were not working correctly for long time, so there is a choice of fixing Linux side while breaking U-boot and not fixing, but keeping bootloader working. Best regards, Krzysztof