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=-8.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham 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 29635C433E2 for ; Wed, 16 Sep 2020 21:31:19 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 8E651206DC for ; Wed, 16 Sep 2020 21:31:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="LENwgxf4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E651206DC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org 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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Mime-Version:References:In-Reply-To:Date:To:From: Subject:Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=TjSaIURZkaRt5NHTbHUWZZTKhfNBW1EoeTdgVJmzSxs=; b=LENwgxf4J/hRhezwgywr9JyBa ynBSpBFygBr1o1paXMUZZme0raxjaUdXw6+6WGmWhWe/U2k/mwdDamOBBt6rPC/IEot0IE0vT0RRh ujf1MeHjK/rbKP5uzHfLY239CwpduNEF81cNiIvdj1GORmxZ4Gjrj1zXuYKN78V12pdsLMDd51wpR ccZbydAk9QMUZZ8wCKcFXPEMeoMSIJRWpYK8c5wcWwWLZ6+q1S5ku/2QaWB57A4YBALhoe6aIDYcQ SFNNNFQRbFXKzCAAPJVm9ybEPPABNy0HtZ3D8wtgc7fe9DC3BI071/Wr3AgJ3cgCCAQEKf8ZeBz8c /9yA2ZQHQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIezj-0004A2-FD; Wed, 16 Sep 2020 21:29:39 +0000 Received: from kernel.crashing.org ([76.164.61.194]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIezg-00049I-Rz for linux-arm-kernel@lists.infradead.org; Wed, 16 Sep 2020 21:29:37 +0000 Received: from localhost (gate.crashing.org [63.228.1.57]) (authenticated bits=0) by kernel.crashing.org (8.14.7/8.14.7) with ESMTP id 08GLTCG0028056 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 16 Sep 2020 16:29:15 -0500 Message-ID: Subject: Re: [PATCH] arm64: Enable PCI write-combine resources under sysfs From: Benjamin Herrenschmidt To: Catalin Marinas , Lorenzo Pieralisi Date: Thu, 17 Sep 2020 07:29:11 +1000 In-Reply-To: <20200916170058.GD3122@gaia> References: <1d6f2ceb8d3538c906a1fdb8cd3d4c74ccffa42e.camel@kernel.crashing.org> <20200914225740.GP904879@nvidia.com> <2b539df4c9ec703458e46da2fc879ee3b310b31c.camel@kernel.crashing.org> <20200915101831.GA2616@e121166-lin.cambridge.arm.com> <20200915110511.GQ904879@nvidia.com> <20200915234006.GI1573713@nvidia.com> <20200916083315.GC27496@willie-the-truck> <20200916084851.GA3122@gaia> <20200916141502.GB20770@e121166-lin.cambridge.arm.com> <20200916170058.GD3122@gaia> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200916_172937_029662_64812D9E X-CRM114-Status: GOOD ( 13.33 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Leon Romanovsky , linux-pci@vger.kernel.org, Bjorn Helgaas , Jason Gunthorpe , Will Deacon , linux-arm-kernel@lists.infradead.org, Clint Sbisa Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 2020-09-16 at 18:00 +0100, Catalin Marinas wrote: > > That we don't know but if a prefetchable BAR can't tolerate read > > side effects this would be already a problem on eg x86 - that's > > the best we can hope for given the current PCI specs. > > > > +1 on normal NC. The only open point is whether we should make > > arch_can_pci_mmap_wc() return false on platforms like TX2. > > I lost track in this thread whether it matters. TX2 would need Device > GRE for optimal performance but the kernel doesn't currently provide > it anyway. We could expose a new memory type, aligned_wc ;). Or ignore TX2 :-) Though Lorenzo has a point about making it return false for arch_can_pci_mmap_wc() if we really care enough. Cheers, Ben. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel