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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 13C84C433E0 for ; Tue, 9 Mar 2021 20:26:18 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 940CE65227 for ; Tue, 9 Mar 2021 20:26:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 940CE65227 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=marcan.st Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:Subject: From:References:Cc:To:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ZwCDSkMDcc8+v375uBdmLELgF3h69sCQqGqPnPgFeso=; b=oBFU3rRyc2SP05mcFgA/Ikoiq 99hS/T3ay63kRefgwz4qS1qCGLXbO20lhrrKGyIUP1oxJIXaVRRmVY/rEPBLSfELPaIhPe8pJyVLi oa4VPOyw4X7jLR7NWGZNiNDfp5oFpU9L2Pa/DPiS1x1vxQHaexedxy6roFd+OxJ+UcuEnFSJRoS7E xU5LoYUNPKw2kibQEaBUpZeAXtYSd/pNo5kMlU/EPTRVHAC9/182rPKkiLtvfaspHtB6cSlAPiQ/e EPPqGKEk/psuqvEAcFesF1WipRxxQxHG/JE7e5DdQM1bAaKcJezQ59iIZmzr/q+5y7p0uIQrpvifj zWyshL7TA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lJitx-005Ltq-Db; Tue, 09 Mar 2021 20:24:21 +0000 Received: from marcansoft.com ([2a01:298:fe:f::2] helo=mail.marcansoft.com) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lJite-005Lrv-4v for linux-arm-kernel@lists.infradead.org; Tue, 09 Mar 2021 20:24:09 +0000 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 E5D233FA6A; Tue, 9 Mar 2021 20:23:49 +0000 (UTC) To: Rob Herring , Arnd Bergmann Cc: 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" 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> From: Hector Martin Subject: Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted Message-ID: Date: Wed, 10 Mar 2021 05:23:47 +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-Language: es-ES X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210309_202403_874324_ED4B2126 X-CRM114-Status: GOOD ( 21.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 10/03/2021 00.48, Rob Herring wrote: > On Mon, Mar 8, 2021 at 2:56 PM Arnd Bergmann wrote: >> >> On Mon, Mar 8, 2021 at 10:14 PM Rob Herring wrote: >>> On Mon, Mar 08, 2021 at 09:29:54PM +0100, Arnd Bergmann wrote: >>>> On Mon, Mar 8, 2021 at 4:56 PM Rob Herring wrote: >>> >>> Let's just stick with 'nonposted-mmio', but drop 'posted-mmio'. I'd >>> rather know if and when we need 'posted-mmio'. It does need to be added >>> to the DT spec[1] and schema[2] though (GH PRs are fine for both). >> >> I think the reason for having "posted-mmio" is that you cannot properly >> define the PCI host controller nodes on the M1 without that: Since >> nonposted-mmio applies to all child nodes, this would mean the PCI >> memory space gets declared as nonposted by the DT, but the hardware >> requires it to be mapped as posted. > > I don't think so. PCI devices wouldn't use any of the code paths in > this patch. They would map their memory space with plain ioremap() > which is posted. My main concern here is that this creates an inconsistency in the device tree representation that only works because PCI drivers happen not to use these code paths. Logically, having "nonposted-mmio" above the PCI controller would imply that it applies to that bus too. Sure, it doesn't matter for Linux since it is ignored, but this creates an implicit exception that PCI buses always use posted modes. Then if a device comes along that due to some twisted fabric logic needs nonposted nGnRnE mappings for PCIe (even though the actual PCIe ops will end up posted at the bus anyway)... how do we represent that? Declare that another "nonposted-mmio" on the PCIe bus means "no, really, use nonposted mmio for this"? -- Hector Martin (marcan@marcan.st) Public Key: https://mrcn.st/pub _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel