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 991DBC433FE for ; Thu, 10 Feb 2022 23:17:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345222AbiBJXRs (ORCPT ); Thu, 10 Feb 2022 18:17:48 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:36200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345151AbiBJXRs (ORCPT ); Thu, 10 Feb 2022 18:17:48 -0500 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8878FB37; Thu, 10 Feb 2022 15:17:48 -0800 (PST) Received: by mail-lj1-x230.google.com with SMTP id c15so10144902ljf.11; Thu, 10 Feb 2022 15:17:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=YBwbR1kfaUcjXLL/JErsVbZh7K8KaPOAlgJd4IsVbZo=; b=itgm2BhEwvfTMxc68Ux/piIvgdWhkdxG8vl3df2oj1msFZ1ZWlT380bgQlANY7Mh2h X+WycdEPITqd/4zalr0KJUbSHM9QHNSRi5PDh22MaqADuCJPXuuFLkQYgC9pxGmevmXx 6XTvJ/x6k/mccGMSOLo00J13yAhAsQJE+/BadNPoSXU6etZP6QSpsUMKqdAzIicJ3KGm jyNEG1Jef6PsWZvWEZxd2KD8f+KmEgOJxVyMQtZLTg2iqtpdx8sI1U0yjBoZ+bidhCHK ocpokCe+ehBN6c2rH8Jr0g2qFFzKmJcKQxe3Finci59H1cRoUwn8ptuDCFmarrgNCUfR neWA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=YBwbR1kfaUcjXLL/JErsVbZh7K8KaPOAlgJd4IsVbZo=; b=sILqZ72fdd+ybUG+g9/zF70gmxN8lr/TX23WXd44haeKjf2tf9zgwuglB2LnESF7ZW eFGWP5/nANH38CO6+tEy9U4O2Ao+mBy3QGusNXhpTsMUyWdbg2WBaYwkJbyXS6JwbzFz rkj+O8UydqpJZiMRQIZ17OtXqGztnjYzpbZjLYs8ioOc4ZpgdFpTsuLMnUf0HswQaAUX Qwg4lZej0WntUeT+SwXQPpoQHOArVfUWGbbSqwoDesGJ9Qw7vRBhyCizzQp3ka1b5sFf Flp53Pu2xOVCUcmu0emT7tMKvKLQZTKqLEP3pmCFnOcbyx9Yge9DmZ16NFpVnO8SPUgQ f0PQ== X-Gm-Message-State: AOAM5304YQlH+Di02KvOUGlPSq2AVBSGaX3UwuQO6ZW59BwNAl+Xz7iI zo5sV9LI83A6RvlIVh1j4FA= X-Google-Smtp-Source: ABdhPJxyjKx22xANHqMYIJ2sFOBupzDvlwNvb6SN7kz1mlL+wLImv7HdWxxuq50N7/N+BbwlDuR98w== X-Received: by 2002:a2e:878f:: with SMTP id n15mr6321873lji.159.1644535066762; Thu, 10 Feb 2022 15:17:46 -0800 (PST) Received: from dimatab (109-252-138-165.dynamic.spd-mgts.ru. [109.252.138.165]) by smtp.gmail.com with ESMTPSA id f30sm1433412lfj.112.2022.02.10.15.17.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Feb 2022 15:17:46 -0800 (PST) Date: Fri, 11 Feb 2022 02:17:39 +0300 From: Dmitry Osipenko To: Julius Werner Cc: Krzysztof Kozlowski , Rob Herring , linux-tegra@vger.kernel.org, Rob Herring , Jonathan Hunter , devicetree@vger.kernel.org, LKML , Thierry Reding Subject: Re: [PATCH v5 3/9] dt-bindings: memory: lpddr2: Add revision-id properties Message-ID: <20220211021739.14f3614c@dimatab> In-Reply-To: References: <20211006224659.21434-1-digetx@gmail.com> <20211006224659.21434-4-digetx@gmail.com> <6568fd31-113f-1581-4eff-45a4a1eb4e5d@canonical.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org =D0=92 Wed, 9 Feb 2022 16:32:25 -0800 Julius Werner =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > > I don't mind, but I also don't see where the revision-id property of > > LPDDR3 is used at all. I can't find any device-tree with LPDDR3 > > revision-id and don't see it being used in the code either. Maybe > > it's the LPDDR3 binding that needs to be changed? =20 >=20 > We are using the revision ID in userspace (read through > /proc/device-tree) for runtime memory identification. We don't have a > kernel driver bound to it. Our boot firmware is inserting this value > at runtime into the FDT (that's basically the reason we have this, our > firmware auto-detects memory during boot and we use the FDT to report > what it found to userspace), that's why you can't find it anywhere in > the static device trees in boot/dts/. Thank you for the clarification. Which device is that and why userspace needs to know so much about memory? > > I made each LPDDR2 revision-id property to correspond to a > > dedicated MR of LPDDR, which feels okay to me to since it matches > > h/w. =20 >=20 > I'm not super married to my solution, so if that makes things easier > we can standardize on the two-property version as well. I mostly > designed it my way because I thought we may one day also want to do > something like this for the 8-byte LPDDR5 serial-id, and then it would > get kinda cumbersome to have serial-id1 through serial-id8 all as > separate properties. But that's also a bridge we can cross when we get > there. >=20 > My use case is in a position where we could still change this now > without requiring backwards-compatibility. Krzysztof, would you be > okay if I instead changed the "jedec,lpddr3" to the same thing > "jedec,lpddr2" does -- seeing as the original patch was from me, my > use case could handle the switch, there has never been any actual > kernel code using the property, and it seems very unlikely that anyone > else has silently started using the same thing in the time it's been > in the tree? Or do we also need to go the official deprecation route > for that? If you're going to use multiple cells for other properties, then indeed will be better to keep it consistent.