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 X-Spam-Level: X-Spam-Status: No, score=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6C18C2BA1A for ; Thu, 11 Mar 2021 18:11:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD16164FD4 for ; Thu, 11 Mar 2021 18:11:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231308AbhCKSLN (ORCPT ); Thu, 11 Mar 2021 13:11:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:55496 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230300AbhCKSKf (ORCPT ); Thu, 11 Mar 2021 13:10:35 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 773FA65018; Thu, 11 Mar 2021 18:10:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615486234; bh=tmt8DXL/NkkK3fqsKzp1sa5x/enHlRdNBSlE6sT3Ol4=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Ew/NIGH8ca6hopkG3U8b9r6qb4RL4623K9fly5yItiT+8ubil19Ek3W1I9uzZkXaV SS/wUSc4qF2N/+CEdEEjiosqyXdPlQDV6gmsZyGoYiofROwQuELtuvpXLsg41ZUl+I zTxb4YH7gGW2lP+bk0UmqouHE1A4Ct9j5CBAZIb/EyFukR+wc5+426TEG3xvSqlTNs zrISTJo7Bcn1PT6Tt7VvH6wBUv/FOVlzZjPhhFRyf24OBWtBR8UkBxZNOxnGayUlL3 qdG/KlD2b/NUv3xynLWzvL7xQCfBHPzi0d+rEqHmljXgXkL98TRQxiPn6hmAPOYpfu pO74we79VATfg== Received: by mail-ej1-f43.google.com with SMTP id e19so48236776ejt.3; Thu, 11 Mar 2021 10:10:34 -0800 (PST) X-Gm-Message-State: AOAM532gIRH9bm3Fo+i0EbsHlRjhxiPQWK5SP7fJE/Yz0D30C1g5zyPH LQhMi4sqcRq0QAngd7NwMBkwIHB/s3Zjf6bAFg== X-Google-Smtp-Source: ABdhPJyUsXPtzO/H83nHUMgfPs1p3wnAlKlkTmdKFFzieSp9RKRftdZy73PPYTvjnRjgXVDraWLRvsEKaxzbwKml2jg= X-Received: by 2002:a17:906:c405:: with SMTP id u5mr4327186ejz.341.1615486232876; Thu, 11 Mar 2021 10:10:32 -0800 (PST) MIME-Version: 1.0 References: <20210304213902.83903-1-marcan@marcan.st> <20210304213902.83903-13-marcan@marcan.st> <6e4880b3-1fb6-0cbf-c1a5-7a46fd9ccf62@marcan.st> <20210308211306.GA2920998@robh.at.kernel.org> <332c0b9a-dcfd-4c3b-9038-47cbda90eb3f@marcan.st> In-Reply-To: From: Rob Herring Date: Thu, 11 Mar 2021 11:10:20 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted To: Arnd Bergmann Cc: Hector Martin , linux-arm-kernel , Marc Zyngier , Olof Johansson , Krzysztof Kozlowski , Mark Kettenis , Tony Lindgren , Mohamed Mediouni , Stan Skowronek , Alexander Graf , Will Deacon , Linus Walleij , Mark Rutland , Andy Shevchenko , Greg Kroah-Hartman , Jonathan Corbet , Catalin Marinas , Christoph Hellwig , "David S. Miller" , DTML , "open list:SERIAL DRIVERS" , Linux Doc Mailing List , linux-samsung-soc , "open list:GENERIC INCLUDE/ASM HEADER FILES" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Thu, Mar 11, 2021 at 9:48 AM Arnd Bergmann wrote: > > On Thu, Mar 11, 2021 at 5:10 PM Rob Herring wrote: > > On Thu, Mar 11, 2021 at 2:12 AM Arnd Bergmann wrote: > > > On Wed, Mar 10, 2021 at 6:01 PM Rob Herring wrote: > > > Ok, makes sense. > > > > > > Conceptually, I'd like to then see a check that verifies that the > > > property is only set for nodes whose parent also has it set, since > > > that is how AXI defines it: A bus can wait for the ack from its > > > child node, or it can acknowledge the write to its parent early. > > > However, this breaks down as soon as a bus does the early ack: > > > all its children by definition use posted writes (as seen by the > > > CPU), even if they wait for stores that come from other masters. > > > > > > Does this make sense to you? > > > > BTW, I don't think it's clear in this thread, but the current > > definition proposed for the spec[1] and schema is 'nonposted-mmio' is > > specific to 'simple-bus'. I like this restriction and we can expand > > where 'nonposted-mmio' is allowed later if needed. > > That sounds ok, as long as we can express everything for the mac > at the moment. Do we need to explicitly add a description to allow > the property in the root node in addition to simple-bus to be able > to enforce the rule about parent buses also having it? IMO it should not be allowed in the root node. That's a failure to define a bus node. Also, would that mean your memory has to be non-posted!? Rob