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=-5.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 8965AC433E2 for ; Thu, 3 Sep 2020 08:43:26 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (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 1207F206C0 for ; Thu, 3 Sep 2020 08:43:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="XYVOBYdf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1207F206C0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 9C38B18C8; Thu, 3 Sep 2020 10:42:34 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 9C38B18C8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1599122604; bh=KWKQwnqvJnx/QhZ5+RbyfmbTY2Ory0CV5zRTjI4Qnc4=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=XYVOBYdfoC7aPvtFFjNgccdCeTnbUFgXM77OwNShFxEkWeGrgRBABgNy4ScjzD1MQ xhu6xtjYbR72jelcrm9lYnVFDf7Y1V9+a6aCHQV/1XHcUFQz6NT0Hsi0UKOeahrsmw h3t6sShiAKO4Y0lZFNgCNcYhJMia2Cl4iHr820Y0= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 3F4EDF801DA; Thu, 3 Sep 2020 10:42:34 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id CB3CEF8021D; Thu, 3 Sep 2020 10:42:31 +0200 (CEST) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 664E6F800BA for ; Thu, 3 Sep 2020 10:42:28 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 664E6F800BA Received: by verein.lst.de (Postfix, from userid 2407) id 2B13F68BEB; Thu, 3 Sep 2020 10:42:27 +0200 (CEST) Date: Thu, 3 Sep 2020 10:42:26 +0200 From: Christoph Hellwig To: Thomas Bogendoerfer Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200903084226.GA24410@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> <20200901173810.GA25282@alpha.franken.de> <20200902213809.GA7998@alpha.franken.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200902213809.GA7998@alpha.franken.de> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-kernel@vger.kernel.org, Kyungmin Park X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Wed, Sep 02, 2020 at 11:38:09PM +0200, Thomas Bogendoerfer wrote: > the patch below fixes the problem. But is very wrong unfortunately. > static inline void dma_sync_desc_cpu(struct net_device *dev, void *addr) > { > - dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc), > - DMA_FROM_DEVICE); > + struct sgiseeq_private *sp = netdev_priv(dev); > + > + dma_sync_single_for_device(dev->dev.parent, VIRT_TO_DMA(sp, addr), > + sizeof(struct sgiseeq_rx_desc), DMA_FROM_DEVICE); > } > > static inline void dma_sync_desc_dev(struct net_device *dev, void *addr) > { > - dma_cache_sync(dev->dev.parent, addr, sizeof(struct sgiseeq_rx_desc), > - DMA_TO_DEVICE); > + struct sgiseeq_private *sp = netdev_priv(dev); > + > + dma_sync_single_for_device(dev->dev.parent, VIRT_TO_DMA(sp, addr), > + sizeof(struct sgiseeq_rx_desc), DMA_TO_DEVICE); This is not how the DMA API works. You can only call dma_sync_single_for_{device,cpu} with the direction that the memory was mapped. It then transfer ownership to the device or the cpu, and the ownership of the memory is a fundamental concept that allows for reasoning about the caching interaction. > } > > -- > Crap can work. Given enough thrust pigs will fly, but it's not necessarily a > good idea. [ RFC1925, 2.3 ] ---end quoted text---