From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=SmZj=WM=lists.ozlabs.org=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@kernel.org>
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=HEADER_FROM_DIFFERENT_DOMAINS,
	INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,
	URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 DD07FC3A59D
	for <linuxppc-dev@archiver.kernel.org>; Fri, 16 Aug 2019 17:58:15 +0000 (UTC)
Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2])
	(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 6BE7B20665
	for <linuxppc-dev@archiver.kernel.org>; Fri, 16 Aug 2019 17:58:15 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6BE7B20665
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3])
	by lists.ozlabs.org (Postfix) with ESMTP id 4699z84shxzDqD9
	for <linuxppc-dev@archiver.kernel.org>; Sat, 17 Aug 2019 03:58:12 +1000 (AEST)
Authentication-Results: lists.ozlabs.org;
 spf=pass (mailfrom) smtp.mailfrom=arm.com
 (client-ip=217.140.110.172; helo=foss.arm.com;
 envelope-from=mark.rutland@arm.com; receiver=<UNKNOWN>)
Authentication-Results: lists.ozlabs.org;
 dmarc=none (p=none dis=none) header.from=arm.com
Received: from foss.arm.com (foss.arm.com [217.140.110.172])
 by lists.ozlabs.org (Postfix) with ESMTP id 4699Th0FhrzDr0f
 for <linuxppc-dev@lists.ozlabs.org>; Sat, 17 Aug 2019 03:36:06 +1000 (AEST)
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 <mark.rutland@arm.com>
To: Will Deacon <will@kernel.org>
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-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20190816173118.4rbbzuogfamfa554@willie-the-truck>
User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01)
X-BeenThere: linuxppc-dev@lists.ozlabs.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Cc: Shawn Anastasio <shawn@anastas.io>, linux-m68k@lists.linux-m68k.org,
 Catalin Marinas <catalin.marinas@arm.com>, linuxppc-dev@lists.ozlabs.org,
 linux-kernel@vger.kernel.org, Russell King <linux@armlinux.org.uk>,
 linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org,
 Geert Uytterhoeven <geert@linux-m68k.org>, Paul Burton <paul.burton@mips.com>,
 James Hogan <jhogan@kernel.org>, Guan Xuetao <gxt@pku.edu.cn>,
 Christoph Hellwig <hch@lst.de>, linux-arm-kernel@lists.infradead.org,
 Robin Murphy <robin.murphy@arm.com>
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.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 <hch@lst.de>
> > ---
> >  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.rutland@arm.com>

Mark.