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 A0CE1C3ABC9 for ; Fri, 16 May 2025 21:42:11 +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:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=0lmpxm/InXkC7gAaYfpV9glaXAIWY25jAT39ISKPw6s=; b=LNL2niePcAjEaht1upnej4maSY Aq9H8oorY7Fljef8iBuw2Sm0K9Fx9QuLmYkOH1bXVS5L57n8USY63KIiVVNA1wvaasmLgUxkUJtpM Lz4hfnzO2hcpbtaTpv3s3KFFJjS4rgFGO2FQaYxhHhSYn+MvvNky5y6LJrePb05vet7EAnQQUei4a tyJWWZE1mAKK5OVGQU7uIin4z+B6BVhxbH7ylOeR5sH9u0s94rs4oAvTHIoelM1/rsdkeSU34ZppH BWOJXatmBmHE2cJLgJe0Tdi+NpV0V+vzGU0Az7OYwYwRBbU2aLlJ7peH1C3XZ/SYTvB/zn2EWHGX1 n3DUB8VA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uG2of-00000004g8V-2mwp; Fri, 16 May 2025 21:42:05 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uG2ih-00000004ev0-34vb for linux-arm-kernel@lists.infradead.org; Fri, 16 May 2025 21:35:57 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 36405437B9; Fri, 16 May 2025 21:35:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90F65C4CEE4; Fri, 16 May 2025 21:35:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747431355; bh=bLyZNDh57twuZ5u/SwC20jaSbr5jsZ/x4elmufChQC0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=sJ/fjkd5HQpsmR9FBzcNfeQ/H4ZUDgUgeEVkg3CnFA1D07wR5QPrWCZEWoAB/Zkeq bMXvO4zDJKbmsyRi0lyTLbG/BdwTJfP90kgMfhHV58sS63MORa7CKZF0gcsEpqEjq0 dFcxnrRK/kroHB4xNmsndNh2953U7dpqscH3sWQVcGo/3HZtSHugB+kP6f9QQsqPIy 3lP67LiGuER55cLqO4dTiwBCXi8i1WyNab2fGB8Lx+THgKH6+vbSNGWvpgPYx8Dy7i 3Wyo9XMyE9418BuuDUKu3zfzBHkze8ckbj0hIl72IgYuY9P0QaPBZJd2hSl9QsLKZY mIh7iNa7VV7Ng== Message-ID: Date: Fri, 16 May 2025 21:44:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 5/6] arm64: dts: ls1028a-qds: make the QIXIS CPLD use the simple-mfd-i2c.c driver To: Vladimir Oltean Cc: Ioana Ciornei , Lee Jones , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Shawn Guo , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20250430153634.2971736-1-ioana.ciornei@nxp.com> <20250430153634.2971736-6-ioana.ciornei@nxp.com> <20250502-savvy-eccentric-hog-b4fed5@kuoka> <8ec115f7-1a35-4506-a20a-b4de27f10960@kernel.org> <7d6b529e-ab26-4efe-8b91-1facbd041ba3@kernel.org> <20250507153811.ukkficut2f3jm2hg@skbuf> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250516_143555_817164_8D92756A X-CRM114-Status: GOOD ( 30.26 ) 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 07/05/2025 17:38, Vladimir Oltean wrote: >> This sounds reasonable, thanks for providing context. Most of this (so a >> summary) should be in the commit msg as the rationale for changing the >> ABI, so please grow a bit the commit msg part: >> "The MDIO mux on the LS1028A-QDS never worked in mainline because ...". >> >> With all this I still do not get why do you need to affect the >> compatibles. What is wrong with the actual compatibles? >> >> Best regards, >> Krzysztof > > I really care about not breaking compatibility with device trees too, > and that's why I occasionally report issues such as > https://lore.kernel.org/all/20250412001703.qbbfhtb6koofvner@skbuf/, > but in this case the compatibility breakage is not something to worry > about. > > The QDS (QorIQ Development System) boards are not made to deploy any > production software on them, they are more fully-featured variants of > our RDB (Reference Design Boards) which sit in labs and are used > exclusively by engineers to test/prototype SoC features in order to > develop for other (production) platforms. Most if not all engineers use > TFTP to load the kernel and device tree at the same time. I think it's > going to be a case of a tree falling in a forest with no one to hear it. OK, this has to be clearly documented so the platform maintainer can understand the impact. > > In terms of other projects using the Linux device tree bindings - in > this case that would be U-Boot, which unfortunately has yet another > schema for the QIXIS CPLD: > https://github.com/u-boot/u-boot/blob/master/arch/arm/dts/fsl-ls1028a-qds.dtsi#L134 > So not really a concern right now, but we will take it as an action item > to resync U-Boot with the upstream device trees for the LS1028A-QDS too, > like was done for the LS1028A-RDB. > > In this case, why would changing the compatible string be preferable to > using the node as is? It would be nice for the QIXIS CPLD to have child > nodes with "reg". The current format lacks that, so we thought it would > be a cleaner break if we just introduced a new compatible string, to So change the current form. I do not see any point in changing compatibles. Whatever your drivers are doing is not really relevant here, because you can change the implementation behind the ABI. > make it easier to distinguish: > - "fsl,ls1028aqds-fpga", "fsl,fpga-qixis-i2c", "simple-mfd" doesn't > expect children with "reg" > - "fsl,ls1028a-qds-qixis-i2c" does. Sorry but no, we are not going to have two different compatibles for the same device. Best regards, Krzysztof