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x-originating-ip: [94.69.234.123] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 356fd88b-93bd-4e45-1136-08d6dfa79dce x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(5600141)(711020)(4605104)(4618075)(2017052603328)(7193020);SRVR:AM0PR0402MB3889; x-ms-traffictypediagnostic: AM0PR0402MB3889: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:6430; x-forefront-prvs: 00462943DE x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(396003)(366004)(346002)(136003)(376002)(39860400002)(189003)(199004)(53936002)(4326008)(53546011)(8936002)(6506007)(316002)(7736002)(305945005)(110136005)(3846002)(74316002)(6246003)(6116002)(5660300002)(66946007)(4744005)(33656002)(76116006)(64756008)(66476007)(66446008)(66556008)(186003)(73956011)(8676002)(476003)(52536014)(66066001)(81166006)(14444005)(81156014)(26005)(9686003)(256004)(102836004)(6436002)(55016002)(99286004)(486006)(229853002)(86362001)(14454004)(446003)(7696005)(44832011)(2906002)(54906003)(25786009)(71200400001)(68736007)(71190400001)(478600001)(76176011);DIR:OUT;SFP:1101;SCL:1;SRVR:AM0PR0402MB3889;H:AM0PR0402MB3476.eurprd04.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: nxp.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: wCx6scCvRm17hTEpxIFGhx9za4I/XyE2oi0K623SOfPjgthZYXIQppRIqqTwgq26MNuYAiJ1JJcNxC/y81FIwF1I7ZUrBXPlzXqBw2wp0i1/Ic98GPluZSIt1jcu//4NbBjFNIs++RDT1oJRooeUuJk/pDxTPGVOxtO4M/t2aK6FD1GNH0SP81LELMhx+4JqcMybP0+IIfsfwVF53+IdlIl2tEq8WEjjVtDkGc5qJcldAMzudttOOKxSzE55oc75n1Zs/L3GahSerGCtPvNUN3NUb5/921j4tvSjJ2JVPQj/tw1jq4PkU3GHeoYDrEAcILqpyssDdTDflC7yRWlgVV6yDRGz/4zxWOFyiMx/8YxAW3HG43vyeLoQLmKut+jAHiYzmqcENb+Q0NS6cw+pEpxMA2dMu0aTyFgckHIO9PU= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: 356fd88b-93bd-4e45-1136-08d6dfa79dce X-MS-Exchange-CrossTenant-originalarrivaltime: 23 May 2019 17:53:51.7974 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM0PR0402MB3889 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/23/2019 7:43 PM, Christoph Hellwig wrote:=0A= > On Thu, May 23, 2019 at 07:35:07AM +0200, Marek Szyprowski wrote:=0A= >> Don't we have DMA_BIDIRECTIONAL for such case?=0A= > =0A= > Not sure if it was intended for that case, but it definitively should=0A= > do the right thing for swiotlb, and it should also do the right thing=0A= > in terms of cache maintainance.=0A= > =0A= >> Maybe we should update =0A= >> documentation a bit to point that DMA_FROM_DEVICE expects the whole =0A= >> buffer to be filled by the device?=0A= > =0A= > Probably. Horia, can you try to use DMA_BIDIRECTIONAL?=0A= > =0A= This works, but at the cost of performance - all the cache lines being writ= ten=0A= back to memory, just to be overwritten by the device.=0A= =0A= Thanks,=0A= Horia=0A=