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=-9.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 33F3AC3A59C for ; Fri, 16 Aug 2019 07:23:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 015DD20644 for ; Fri, 16 Aug 2019 07:23:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="cYrzgGco" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727182AbfHPHXj (ORCPT ); Fri, 16 Aug 2019 03:23:39 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46960 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726166AbfHPHXi (ORCPT ); Fri, 16 Aug 2019 03:23:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From :Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=V5Zw49kQPZrMPdAV7XGYxZ4KnGSn0pXrZQuwIbjovPc=; b=cYrzgGcooFyvmagoHDTahcizcr ulAhAjBwfwJ77g7fjQVCrejwUPdW3+451tmr4XYxlVX8GxKY6cn3W8XzSqaVepJUUvLLtSTSTGMS2 D6pUyCdbRYLrAnYboEv/JXnpSBpVixFIvWgyIfF5md8ZZXHK3JZ1uZkdsSR/CUj+a7OAuiX/QKZ4f IxilPeoBwYRLMyeTi9CQjAPYTO5lWlcHXkdKE5px7Tm0Z5Uv09MdQjAqWuzskLMQWZVz71rZHpeY5 mK5d/REaLrxG8p8FjuCzLwlM5I1DLEWp0Hs1N6GdEsdYKhkTSq8vu8t5mK7Hc4pyUMSFWtRpfVilP iCSS6GWw==; Received: from 089144199030.atnat0008.highway.a1.net ([89.144.199.30] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hyWa8-0003qQ-O9; Fri, 16 Aug 2019 07:23:29 +0000 From: Christoph Hellwig To: iommu@lists.linux-foundation.org Cc: Guan Xuetao , Shawn Anastasio , Russell King , Catalin Marinas , Will Deacon , Robin Murphy , Paul Burton , James Hogan , Geert Uytterhoeven , linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org Subject: [PATCH 6/6] arm64: document the choice of page attributes for pgprot_dmacoherent Date: Fri, 16 Aug 2019 09:07:54 +0200 Message-Id: <20190816070754.15653-7-hch@lst.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190816070754.15653-1-hch@lst.de> References: <20190816070754.15653-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. + */ #define pgprot_dmacoherent(prot) \ __pgprot_modify(prot, PTE_ATTRINDX_MASK, \ PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) -- 2.20.1