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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 05E72C433E9 for ; Fri, 5 Mar 2021 17:20:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBFE9650A1 for ; Fri, 5 Mar 2021 17:20:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229486AbhCERTl (ORCPT ); Fri, 5 Mar 2021 12:19:41 -0500 Received: from marcansoft.com ([212.63.210.85]:33278 "EHLO mail.marcansoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229465AbhCERTf (ORCPT ); Fri, 5 Mar 2021 12:19:35 -0500 Received: from [127.0.0.1] (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: marcan@marcan.st) by mail.marcansoft.com (Postfix) with ESMTPSA id 0610042037; Fri, 5 Mar 2021 17:19:25 +0000 (UTC) Subject: Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted To: Arnd Bergmann , Andy Shevchenko Cc: linux-arm Mailing List , Marc Zyngier , Rob Herring , Olof Johansson , Krzysztof Kozlowski , Mark Kettenis , Tony Lindgren , Mohamed Mediouni , Stan Skowronek , Alexander Graf , Will Deacon , Linus Walleij , Mark Rutland , Greg Kroah-Hartman , Jonathan Corbet , Catalin Marinas , Christoph Hellwig , "David S. Miller" , devicetree , "open list:SERIAL DRIVERS" , Linux Documentation List , Linux Samsung SOC , Linux-Arch , Linux Kernel Mailing List References: <20210304213902.83903-1-marcan@marcan.st> <20210304213902.83903-13-marcan@marcan.st> <04ea35d6-cd7d-d6de-75ae-59b1e0c77f04@marcan.st> From: Hector Martin Message-ID: <7c56c08f-9382-5db4-647a-1afae79c84de@marcan.st> Date: Sat, 6 Mar 2021 02:19:23 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: es-ES Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On 06/03/2021 01.43, Arnd Bergmann wrote: > - setting ioremap() on PCI buses non-posted only makes them > only slower but not more reliable, because the non-posted flag > on the bus is discarded by the PCI host bridge. Note that this doesn't work here *anyway*. The fabric is picky in both directions: thou shalt use nGnRnE for on-SoC MMIO and nGnRE for PCIe windows, or else, SError. Since these devices can support *any* PCI device via Thunderbolt, making PCI drivers be the oddball ones needing special APIs would mean hundreds of changes needed - the vast majority of PCI drivers in the kernel use plain ioremap variants that don't have any flags to look at. -- Hector Martin (marcan@marcan.st) Public Key: https://mrcn.st/pub