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=-7.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 BCF44C433E2 for ; Fri, 11 Sep 2020 18:01:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7BCFA22206 for ; Fri, 11 Sep 2020 18:01:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="p3td48Cv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725846AbgIKSBf (ORCPT ); Fri, 11 Sep 2020 14:01:35 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:46044 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725794AbgIKSBd (ORCPT ); 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Fri, 11 Sep 2020 18:01:00 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 08BHximb049957; Fri, 11 Sep 2020 18:00:59 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 33dacqayvf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 11 Sep 2020 18:00:59 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 08BI0t3G026796; Fri, 11 Sep 2020 18:00:55 GMT Received: from [10.74.108.237] (/10.74.108.237) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 11 Sep 2020 11:00:55 -0700 Subject: Re: [PATCH 2/3] ARM/keystone: move the DMA offset handling under ifdef CONFIG_ARM_LPAE To: Russell King - ARM Linux admin , Christoph Hellwig Cc: iommu@lists.linux-foundation.org, Santosh Shilimkar , Jim Quinlan , Nathan Chancellor , Florian Fainelli , Robin Murphy , Rob Herring , Frank Rowand , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sh@vger.kernel.org, linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, linux-usb@vger.kernel.org References: <20200910054038.324517-1-hch@lst.de> <20200910054038.324517-3-hch@lst.de> <20200911111551.GG1551@shell.armlinux.org.uk> From: santosh.shilimkar@oracle.com Organization: Oracle Corporation Message-ID: Date: Fri, 11 Sep 2020 11:00:52 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200911111551.GG1551@shell.armlinux.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9741 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 bulkscore=0 phishscore=0 adultscore=0 suspectscore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009110145 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9741 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 priorityscore=1501 mlxlogscore=999 mlxscore=0 bulkscore=0 suspectscore=0 spamscore=0 malwarescore=0 phishscore=0 lowpriorityscore=0 clxscore=1011 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009110145 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 9/11/20 4:15 AM, Russell King - ARM Linux admin wrote: > On Thu, Sep 10, 2020 at 07:40:37AM +0200, Christoph Hellwig wrote: >> The DMA offset notifier can only be used if PHYS_OFFSET is at least >> KEYSTONE_HIGH_PHYS_START, which can't be represented by a 32-bit >> phys_addr_t. Currently the code compiles fine despite that, a pending >> change to the DMA offset handling would create a compiler warning for >> this case. Add an ifdef to not compile the code except for LPAE >> configs. > > However, to have use of the high physical offset, LPAE needs to be > enabled, which ensures that phys_addr_t is 64-bit. > > I believe that DMA is non-coherent on this platform unless the high > physical address is used. Or something like that. > Exactly. Higher address ranges needs to be used for DMA coherency. Regards, Santosh