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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB32BC54EE9 for ; Sun, 18 Sep 2022 09:09:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229497AbiIRJJM (ORCPT ); Sun, 18 Sep 2022 05:09:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229458AbiIRJJL (ORCPT ); Sun, 18 Sep 2022 05:09:11 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B67525592; Sun, 18 Sep 2022 02:09:10 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 9ADBAB80E84; Sun, 18 Sep 2022 09:09:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FDECC433D6; Sun, 18 Sep 2022 09:09:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663492148; bh=B7fP5yqOD5w51+NcW1DLKEZMR0ScOvN08QLqwn27G28=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=DXDujb66dU2W00XcxCBGfpuKOJNMHAbuaKIC2XcGEoiPhC351/tf5LJmFiC6rhOI6 4na9sbhafjDnez3rVWTHBxWWRWlRGca3RtU06uQksboqAjTg+z2+dLdiO6RaGLuZLR FipgWOHDhEv7IiCwtQUUqSaEOeaE6Cbwoq+znM8SmIaxEAhBf8yNjVZHcVdfiQ0QnM IlTKIxSLE0I0mfd2hxapIw1PqRUJBE0OT6DrIdWtWXl+vOlYag8NMowmWJUHG3Ri9F du1fIxe9eN2u0Sjw4a1jiTg/AQgMqdVMukgRQCL4k6duUvC7D+k6StsTc2d/z/tsMa JhyWPB4pKEsdw== Received: from 185-176-101-241.host.sccbroadband.ie ([185.176.101.241] helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1oZqIT-00AsAu-TB; Sun, 18 Sep 2022 10:09:06 +0100 Date: Sun, 18 Sep 2022 10:09:05 +0100 Message-ID: <87h715kq1a.wl-maz@kernel.org> From: Marc Zyngier To: Krzysztof Kozlowski Cc: Jean-Philippe Brucker , mark.rutland@arm.com, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH] dt-bindings: timer: Add QEMU compatible strings In-Reply-To: References: <20220916132959.1910374-1-jean-philippe@linaro.org> <0acc2a21-27c2-ec85-0335-263d70c24469@linaro.org> <87mtaxltwm.wl-maz@kernel.org> 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") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.176.101.241 X-SA-Exim-Rcpt-To: krzysztof.kozlowski@linaro.org, jean-philippe@linaro.org, mark.rutland@arm.com, robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Sun, 18 Sep 2022 09:50:58 +0100, Krzysztof Kozlowski wrote: > > On 17/09/2022 19:47, Marc Zyngier wrote: > > On Sat, 17 Sep 2022 17:51:20 +0100, > > Krzysztof Kozlowski wrote: > >> > >> On 16/09/2022 14:30, Jean-Philippe Brucker wrote: > >>> QEMU uses both "arm,armv8-timer" and "arm,armv7-timer" as compatible > >>> string. Although it is unlikely that any guest relies on this, we can't > >>> be certain of that. Therefore, add these to the schema. Clean up the > >>> compatible list a little while at it. > >>> > >>> Signed-off-by: Jean-Philippe Brucker > >> > >> I guess you wanted to say QEMU uses "arm,armv8-timer" followed by > >> "arm,armv7-timer", because otherwise I would understand it that either > >> that or that. Anyway, is it a valid (virtualized) hardware? Is ARMv8 > >> timer really, really compatible with ARMv7 one? > > > > Yes. There isn't a shred of difference between the two in the earlier > > revisions of the ARMv8 architecture, and none of the differences > > introduced in later revisions are exposed to DT anyway. > > > >> I don't think we should document invalid setups out-of-tree, just > >> because they are there, and something like this was also expressed by Rob: > >> https://lore.kernel.org/all/20220518163255.GE3302100-robh@kernel.org/ > > > > This is, on the contrary, something that is perfectly valid. For > > example, a system running a 32bit OS on a 64bit system is perfectly > > entitled to expose both (v8 because that's what the HW is, v7 because > > that's what the OS is the most likely to understand). > > > > You may find it odd, but that: > > > > - expresses something that is actually required > > > > - is what I, as the original author of this binding, have always > > considered valid > > > > - has been valid for a long time (10+ years) before you decided it > > suddenly wasn't > > > > I understand that the "DT police" has high standards, but this has > > been around for much longer, and it isn't because the conversion to > > schema is imperfect that you can rewrite history. > > > > As for the patch, I'd remove the QEMU reference and the deprecation. > > This format is perfectly allowed, and is in use in most VMMs out > > there. Yes, DT is an ABI. > > Thanks for the explanation, actually enough was to say that it is > perfectly valid combination describing hardware. :) Assuming that the original posting was wrong without understanding the context is what triggered it. It is absolutely fine not to know these things, but in this case *do ask questions* rather than dismiss the patch off the bat based of third hand conclusions. Now at least you have the full picture. M. -- Without deviation from the norm, progress is not possible.