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 EE985C433F5 for ; Tue, 14 Dec 2021 11:12:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=sgfZ/xgWRFAK4i3WKrJL/1tyNhriN+5PKOhgSQDlU4I=; b=4IP/5cBN/xlOCE d3kFaktVENgHHxEqsbC6a1ZALESzTZzvcls6+Kk7EkqXb/u30zohS4ReL+bIU7bGlwPXyu/u0AvS5 6BcNBkWb5ZCf3lvn9/uq+Pd7Y3FixK6bz4T+9OXlugUBCfqNw+W3F+E8Ch0z4bH3D6I7lhYX37nNV sh2tjJkRWqZNydg1O5dwCacaqaTtXr3voiNlIqv/L/5bqp2C64ZZDnsbX+f96GJyLn1o2PiTMrq9A P/X27/rB5Lvp6ohCA2KTKk/Jx7NQBtY7oXH9QU8niwW4OqhvOVKbvxycukB0VgmlCm2qrnm1q64/L eHK5FKcoNoGr1N4EHPAw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mx5iW-00Deqv-Lx; Tue, 14 Dec 2021 11:11:32 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mx5iT-00Depx-29 for linux-arm-kernel@lists.infradead.org; Tue, 14 Dec 2021 11:11:30 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 981636146E; Tue, 14 Dec 2021 11:11:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06D47C34606; Tue, 14 Dec 2021 11:11:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1639480288; bh=3vwoTDt+FYHzpmZUz7PHdcv1c6oH6F97ZVEaheZyOSM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=McSCgt8o5IzxGHrkJQ2nsaSpx9bsu4W++S+rWlemDcYaaOYhj+VUfzn7juZgDlK1T 5zCdzkGWn00RBEvHNH93PMirnDn/V3Jss+RLaP95bXyhypptO9U9Y+hiYokXsrbi4e WY2tJF0jsalRts19cf9DrKJFrCin89j7yjG7SZ+2nEV3z2S9gPskHadFQs8FB224Pq GNstVwgj602y7dFdRpugUXBfoxLCJvsHlzczMEpk09JmV6W6Ebwfs7p7BOyUJJSksW oPTB7gIEgP0Z7Lw7savLDQH4ouqHl4O2EtMR+dkVQ/FTjmW4mHwrnFsbq+utY2QSnB MbKnEiERDmukQ== Received: from cfbb000407.r.cam.camfibre.uk ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mx5iQ-00C1lL-3p; Tue, 14 Dec 2021 11:11:26 +0000 Date: Tue, 14 Dec 2021 11:11:25 +0000 Message-ID: <877dc7jvaa.wl-maz@kernel.org> From: Marc Zyngier To: Vladimir Oltean Cc: "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Rob Herring , Shawn Guo , Leo Li , Biwen Li , "Z.Q. Hou" , Kurt Kanzenbach , Rasmus Villemoes Subject: Re: [RFC PATCH devicetree 00/10] Do something about ls-extirq interrupt-map breakage In-Reply-To: <20211214105316.aibjmwdhg7a5wwlj@skbuf> References: <20211214013800.2703568-1-vladimir.oltean@nxp.com> <87ilvrk1r0.wl-maz@kernel.org> <20211214095853.4emzycaxkuqr4tun@skbuf> <87czlzjxmz.wl-maz@kernel.org> <20211214103025.wnzkfxr5xxeuhpln@skbuf> <87a6h3jwrc.wl-maz@kernel.org> <20211214105316.aibjmwdhg7a5wwlj@skbuf> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: vladimir.oltean@nxp.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, robh+dt@kernel.org, shawnguo@kernel.org, leoyang.li@nxp.com, biwen.li@nxp.com, zhiqiang.hou@nxp.com, kurt@linutronix.de, linux@rasmusvillemoes.dk X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211214_031129_208550_87BCDEB0 X-CRM114-Status: GOOD ( 46.07 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 14 Dec 2021 10:53:16 +0000, Vladimir Oltean wrote: > > On Tue, Dec 14, 2021 at 10:39:35AM +0000, Marc Zyngier wrote: > > On Tue, 14 Dec 2021 10:30:26 +0000, > > Vladimir Oltean wrote: > > > > > > On Tue, Dec 14, 2021 at 10:20:36AM +0000, Marc Zyngier wrote: > > > > On Tue, 14 Dec 2021 09:58:54 +0000, > > > > Vladimir Oltean wrote: > > > > > > > > > > Hi Marc (with a c), > > > > > > > > > > I wish the firmware for these SoCs was smart enough to be compatible > > > > > with the bindings that are in the kernel and provide a blob that the > > > > > kernel could actually use. Some work has been started there and this is > > > > > work in progress. True, I don't know what other OF-based firmware some > > > > > other customers may use, but I trust it isn't a lot more advanced than > > > > > what U-Boot currently has :) > > > > > > > > > > Also, the machines may have been in the wild for years, but the > > > > > ls-extirq driver was added in November 2019. So not with the > > > > > introduction of the SoC device trees themselves. That isn't so long ago. > > > > > > > > > > As for compatibility between old kernel and new DT: I guess you'll hear > > > > > various opinions on this one. > > > > > https://www.spinics.net/lists/linux-mips/msg07778.html > > > > > > > > > > | > Are we okay with the new device tree blobs breaking the old kernel? > > > > > | > > > > > | From my point of view, newer device trees are not required to work on > > > > > | older kernel, this would impose an unreasonable limitation and the use > > > > > | case is very limited. > > > > > > > > My views are on the opposite side. DT is an ABI, full stop. If you > > > > change something, you *must* guarantee forward *and* backward > > > > compatibility. That's because: > > > > > > > > - you don't control how updatable the firmware is > > > > > > > > - people may need to revert to other versions of the kernel because > > > > the new one is broken > > > > > > > > - there are plenty of DT users beyond Linux, and we are not creating > > > > bindings for Linux only. > > > > > > > > You may disagree with this, but for the subsystems I maintain, this is > > > > the rule I intent to stick to. > > > > > > That's an honorable set of guiding principles, but how do you apply them > > > here? Reverting Rob's change won't fix the past, and updating the code > > > to account for one format will break the other. As for trying one > > > format, and if there's an error try the other, there may be situations > > > in which you accept invalid input as valid. > > > > maz@hot-poop:~/arm-platforms$ git describe --contains 869f0ec048dc --match=v\* > > v5.16-rc1~125^2~19^2~16 > > > > This patch landed in -rc1, and isn't part of any release. Just revert > > it, and no damage is done. > > The revert is one of the patches posted here. It will fix the problem > short-term but it may not be enough long-term. I think Rob is working on > some sort of validation for "interrupt-map" and this is how the apparently > non-conformant property was brought to his attention. It will trigger > validation warnings that I'm afraid will be tempting for many to "fix". Then build an annotation mechanism for the warning not to fire for quirked systems. > Thus the rest of the patches. Maybe it's just me, but between having to > play a whack-a-mole game and snapping compatibility of old kernels with > new DT blobs, I think more time is lost with the latter. I said what I had to say on the subject, and when it comes to wasted time, that's more than enough. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel