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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 5D9D0C282CE for ; Wed, 22 May 2019 13:34:36 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 3C73120879 for ; Wed, 22 May 2019 13:34:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3C73120879 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id CA6A9D9C; Wed, 22 May 2019 13:34:25 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 45486D73 for ; Wed, 22 May 2019 13:34:24 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id D5068879 for ; Wed, 22 May 2019 13:34:23 +0000 (UTC) Received: by newverein.lst.de (Postfix, from userid 2407) id 2550C67358; Wed, 22 May 2019 15:34:01 +0200 (CEST) Date: Wed, 22 May 2019 15:34:00 +0200 From: Christoph Hellwig To: Robin Murphy Subject: Re: [PATCH] swiotlb: sync buffer when mapping FROM_DEVICE Message-ID: <20190522133400.GA27229@lst.de> References: <20190522072018.10660-1-horia.geanta@nxp.com> <20190522123243.GA26390@lst.de> <6cbe5470-16a6-17e9-337d-6ba18b16b6e8@arm.com> <20190522130921.GA26874@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Horia =?utf-8?Q?Geant=C4=83?= , Konrad Rzeszutek Wilk , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-imx@nxp.com, Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Wed, May 22, 2019 at 02:25:38PM +0100, Robin Murphy wrote: > Sure, but that should be irrelevant since the effective problem here is in > the sync_*_for_cpu direction, and it's the unmap which nobbles the buffer. > If the driver does this: > > dma_map_single(whole buffer); > > dma_unmap_single(whole buffer); > > > then it could instead do this and be happy: > > dma_map_single(whole buffer, SKIP_CPU_SYNC); > > dma_sync_single_for_cpu(updated part of buffer); > dma_unmap_single(whole buffer, SKIP_CPU_SYNC); > Assuming the driver knows how much was actually DMAed this would solve the issue. Horia, does this work for you? _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT 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 AF981C282CE for ; Wed, 22 May 2019 13:34:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BE2920879 for ; Wed, 22 May 2019 13:34:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729482AbfEVNeY (ORCPT ); Wed, 22 May 2019 09:34:24 -0400 Received: from verein.lst.de ([213.95.11.211]:39603 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728827AbfEVNeY (ORCPT ); Wed, 22 May 2019 09:34:24 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id 2550C67358; Wed, 22 May 2019 15:34:01 +0200 (CEST) Date: Wed, 22 May 2019 15:34:00 +0200 From: Christoph Hellwig To: Robin Murphy Cc: Christoph Hellwig , Horia =?utf-8?Q?Geant=C4=83?= , Konrad Rzeszutek Wilk , Marek Szyprowski , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-imx@nxp.com Subject: Re: [PATCH] swiotlb: sync buffer when mapping FROM_DEVICE Message-ID: <20190522133400.GA27229@lst.de> References: <20190522072018.10660-1-horia.geanta@nxp.com> <20190522123243.GA26390@lst.de> <6cbe5470-16a6-17e9-337d-6ba18b16b6e8@arm.com> <20190522130921.GA26874@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 22, 2019 at 02:25:38PM +0100, Robin Murphy wrote: > Sure, but that should be irrelevant since the effective problem here is in > the sync_*_for_cpu direction, and it's the unmap which nobbles the buffer. > If the driver does this: > > dma_map_single(whole buffer); > > dma_unmap_single(whole buffer); > > > then it could instead do this and be happy: > > dma_map_single(whole buffer, SKIP_CPU_SYNC); > > dma_sync_single_for_cpu(updated part of buffer); > dma_unmap_single(whole buffer, SKIP_CPU_SYNC); > Assuming the driver knows how much was actually DMAed this would solve the issue. Horia, does this work for you?