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 510BAD116F3 for ; Wed, 3 Dec 2025 08:31:01 +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-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=47Oi92m+jF3e9mwd+fo0tBe+IYA4+obAYaYhdQgU5yc=; b=qHxWhcL1uuQlqzFfK8AwbEcHKx S7fak6T93c1PopC8Axp50pHQDvdm8gEz5UYd5zyhXRYLY9+AtVPXDPO3Ks5f8Cu8LgC2jK17IPP8w LUs+1fk0xygWJJb1jHp8JplFuJEjH+bTbcqyTeMbpL8gACgM61e03ojhrQ2Oiad2pQ6Z07gXKKXua mXXkvDM5wrIoVFlOuZVQo/7RCWJ6hsigWOYpv+5/tRjQs5giJcu0UzGmB6PJrZG1FTI8/x6bX91lE OqU4ULDykaguai0WJD19NuNS5KVmgqmzK0zBmWM8xP0/kc1TOfhMFHVSWq+HQL6yqwHE/Utt1g+Dh qr8fDJgA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQiGD-00000006JUl-40Hn; Wed, 03 Dec 2025 08:30:53 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vQiGB-00000006JUQ-1epj for linux-arm-kernel@lists.infradead.org; Wed, 03 Dec 2025 08:30:52 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id A552F43AF1; Wed, 3 Dec 2025 08:30:49 +0000 (UTC) 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251202135605.053ada96@kmaincent-XPS-13-7390> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251203_003051_497817_AF29DB3E X-CRM114-Status: GOOD ( 38.22 ) 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 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