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=-5.3 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 44BF0C433DF for ; Tue, 25 Aug 2020 13:27:14 +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 C236F20738 for ; Tue, 25 Aug 2020 13:27:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="MC8C3tKL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C236F20738 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 4F94915F9; Tue, 25 Aug 2020 15:26:22 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 4F94915F9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1598362032; bh=auAhAn2yD37hRadVJ8AIJb2mkAa/xt+a3duiyM5B8pc=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=MC8C3tKL2bZEH6JoCbPGdswcZJRWBMeAFTEs8OlylwUMRszCdGJtL3wmdDVzJpv3y o1lnjBFtdSUtIz402VM8m9rJl2DC2TaeLik2aBu9FPGx3l+aFsvcwpPG8BGRGXdaK7 7BGBXsOsv16bIKvtOM1vvBsvpvTmpk632V6Q4dkw= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id E201FF8025A; Tue, 25 Aug 2020 15:26:21 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id E5299F80260; Tue, 25 Aug 2020 15:26:20 +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 80FD2F80143 for ; Tue, 25 Aug 2020 15:26:13 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 80FD2F80143 Received: by verein.lst.de (Postfix, from userid 2407) id 6E33E68BEB; Tue, 25 Aug 2020 15:26:12 +0200 (CEST) Date: Tue, 25 Aug 2020 15:26:12 +0200 From: Christoph Hellwig To: Marek Szyprowski Subject: Re: a saner API for allocating DMA addressable pages Message-ID: <20200825132612.GA22318@lst.de> References: <20200819065555.1802761-1-hch@lst.de> <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> 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-kernel@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Christoph Hellwig , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, Kyungmin Park , Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, Thomas Bogendoerfer , linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org 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 Tue, Aug 25, 2020 at 01:30:41PM +0200, Marek Szyprowski wrote: > I really wonder what is the difference between this new API and > alloc_pages(GFP_DMA, n). Is this API really needed? I thought that this > is legacy thing to be removed one day... The difference is that the pages returned are guranteed to be addressable by the devie. This is a very important difference that matters for a lot of use cases.