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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hyg93-0002MX-Jh; Fri, 16 Aug 2019 17:36:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hyg90-0002Lq-QX for linux-arm-kernel@lists.infradead.org; Fri, 16 Aug 2019 17:36:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1FB0928; Fri, 16 Aug 2019 10:36:04 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1BA173F694; Fri, 16 Aug 2019 10:36:02 -0700 (PDT) Date: Fri, 16 Aug 2019 18:36:00 +0100 From: Mark Rutland To: Will Deacon Subject: Re: [PATCH 6/6] arm64: document the choice of page attributes for pgprot_dmacoherent Message-ID: <20190816173559.GB7417@lakrids.cambridge.arm.com> References: <20190816070754.15653-1-hch@lst.de> <20190816070754.15653-7-hch@lst.de> <20190816173118.4rbbzuogfamfa554@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190816173118.4rbbzuogfamfa554@willie-the-truck> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190816_103606_905553_D065CF57 X-CRM114-Status: GOOD ( 22.17 ) 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: Shawn Anastasio , linux-m68k@lists.linux-m68k.org, Catalin Marinas , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Russell King , linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org, Geert Uytterhoeven , Paul Burton , James Hogan , Guan Xuetao , Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Robin Murphy Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 16, 2019 at 06:31:18PM +0100, Will Deacon wrote: > Hi Christoph, > > Thanks for spinning this into a patch. > > On Fri, Aug 16, 2019 at 09:07:54AM +0200, Christoph Hellwig wrote: > > Based on an email from Will Deacon. > > > > Signed-off-by: Christoph Hellwig > > --- > > arch/arm64/include/asm/pgtable.h | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > > index 6700371227d1..6ff221d9a631 100644 > > --- a/arch/arm64/include/asm/pgtable.h > > +++ b/arch/arm64/include/asm/pgtable.h > > @@ -435,6 +435,14 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd) > > __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) > > #define pgprot_device(prot) \ > > __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN) > > +/* > > + * DMA allocations for non-coherent devices use what the Arm architecture calls > > + * "Normal non-cacheable" memory, which permits speculation, unaligned accesses > > + * and merging of writes. This is different from "Strongly Ordered" memory > > + * which is intended for MMIO and thus forbids speculation, preserves access > > + * size, requires strict alignment and also forces write responses to come from > > + * the endpoint. > > + */ > > Mind if I tweak the second sentence to be: > > This is different from "Device-nGnR[nE]" memory which is intended for MMIO > and thus forbids speculation, preserves access size, requires strict > alignment and can also force write responses to come from the endpoint. > > ? It's a small change, but it better fits with the arm64 terminology > ("strongly ordered" is no longer used in the architecture). > > If you're happy with that, I can make the change and queue this patch > for 5.4. FWIW, with that wording: Acked-by: Mark Rutland Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel