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 D6A55C4332F for ; Tue, 1 Nov 2022 17:34:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230491AbiKAReP (ORCPT ); Tue, 1 Nov 2022 13:34:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230185AbiKARcV (ORCPT ); Tue, 1 Nov 2022 13:32:21 -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 7FCD31C416; Tue, 1 Nov 2022 10:32:18 -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 41BB0B81EA8; Tue, 1 Nov 2022 17:32:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBF8EC433D6; Tue, 1 Nov 2022 17:32:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667323936; bh=eOjxTt1qzXYpd+vexpbm9/lLy1/vQDQwdcCuCWSj0Kk=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=J0HsDOslmUL61WbPEA56amtuHWxp+nZ1i1E6yiLPJeZblYnRKfC0i9ZpOIdmQNtb3 jWruSl4BgReiqOHRbzVIk9r3KGePf0Tt/EM6NR6gm++9wTfCr9R8F+SpZUN/VCWmLg o8anPKsN8cf/zQ+hb9VVeTTejuUPXtHqb6N6dQnCUzPzbbuP8TUxMM4rciWWUsQ5gd THyo84rpDPnZZdlXALPdpT7KVi3t8GMW2H6MjxfKDgPAlrgsolxEdgxXBfVZUtj99P zMri+hT6IOAqi2ZKCGBsFnFQ+ZFgGXz6WtHFxvblsBJ8Z0ocNwtviKj+UQrZ4EW6jG kLwxE3lnp+phw== Received: by mail-lf1-f50.google.com with SMTP id g12so24448660lfh.3; Tue, 01 Nov 2022 10:32:15 -0700 (PDT) X-Gm-Message-State: ACrzQf3rOh6px4PBH6DcenVPghp/rmRNYrGhp0uatEopQyHaf/dfzDbD AwWRY6cCzzRaDFdeodNHHpyrY8GgV4GdgTfNOA== X-Google-Smtp-Source: AMsMyM55ZQx6ERNnT2ewevQAIODBodrEpIuNlVPuqGNhSoa1jfV7LFjGf9SbOgrxVTM/C2na9B1/Xga8hv/kvtwUcbk= X-Received: by 2002:a05:6512:3e10:b0:4a2:48c1:8794 with SMTP id i16-20020a0565123e1000b004a248c18794mr7390625lfv.17.1667323934009; Tue, 01 Nov 2022 10:32:14 -0700 (PDT) MIME-Version: 1.0 References: <20221028225519.89210-1-paul@crapouillou.net> <20221028225519.89210-2-paul@crapouillou.net> <20221031192341.GA3270129-robh@kernel.org> In-Reply-To: From: Rob Herring Date: Tue, 1 Nov 2022 12:32:05 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/4] dt-bindings: rtc: ingenic: Rework compatible strings and add #clock-cells To: Paul Cercueil Cc: Alessandro Zummo , Alexandre Belloni , Krzysztof Kozlowski , linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, od@opendingux.net Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 31, 2022 at 2:41 PM Paul Cercueil wrote: > > Hi Rob, > > Le lun. 31 oct. 2022 =C3=A0 14:23:41 -0500, Rob Herring = a > =C3=A9crit : > > On Fri, Oct 28, 2022 at 11:55:16PM +0100, Paul Cercueil wrote: > >> The RTC in the JZ4770 is compatible with the JZ4760, but has an > >> extra > >> register that permits to configure the behaviour of the CLK32K pin. > >> The > >> same goes for the RTC in the JZ4780. > >> > >> Therefore, the ingenic,jz4770-rtc and ingenic,jz4780-rtc strings do > >> not > >> fall back anymore to ingenic,jz4760-rtc. The ingenic,jz4780-rtc > >> string > >> now falls back to the ingenic,jz4770-rtc string. > > > > This is a compatibility mess. There is no driver support in v6.1-rc > > for > > ingenic,jz4770-rtc, so a new DT would not work with existing kernels. > > It > > sounds like you need 3 compatibles for 4780. > > Do newer DTs need to work with older kernels? I always assumed the > compatibility was only enforced for the other way around. For a stable platform, yes. Would you want a firmware update carrying the DT to break an existing OS install? Compatibility either way ultimately is up to the platform whether you care or not. I just ask that the commit msg spell that out. In this case, it is easily avoided. Rob