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. 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, 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 63BE8C433E1 for ; Tue, 25 Aug 2020 13:26:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4896220639 for ; Tue, 25 Aug 2020 13:26:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726158AbgHYN0S (ORCPT ); Tue, 25 Aug 2020 09:26:18 -0400 Received: from verein.lst.de ([213.95.11.211]:58839 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbgHYN0S (ORCPT ); Tue, 25 Aug 2020 09:26:18 -0400 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 Cc: Christoph Hellwig , Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Ben Skeggs , Pawel Osciak , Matt Porter , iommu@lists.linux-foundation.org, Tom Lendacky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, netdev@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-mm@kvack.org, alsa-devel@alsa-project.org 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) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org 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. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Tue, 25 Aug 2020 13:26:12 +0000 Subject: Re: a saner API for allocating DMA addressable pages Message-Id: <20200825132612.GA22318@lst.de> List-Id: References: <20200819065555.1802761-1-hch@lst.de> <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> In-Reply-To: <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Marek Szyprowski Cc: Christoph Hellwig , Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Ben Skeggs , Pawel Osciak , Matt Porter , iommu@lists.linux-foundation.org, Tom Lendacky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop.org, netdev@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-mm@kvack.org, alsa-devel@alsa-project.org 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. 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, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 D0E32C433DF for ; Tue, 25 Aug 2020 13:26:23 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 A309D20639 for ; Tue, 25 Aug 2020 13:26:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A309D20639 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 localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 718A486B1A; Tue, 25 Aug 2020 13:26:23 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BtEIFNZTLNGi; Tue, 25 Aug 2020 13:26:20 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id A575086B02; Tue, 25 Aug 2020 13:26:20 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 96137C016F; Tue, 25 Aug 2020 13:26:20 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 725AFC0051 for ; Tue, 25 Aug 2020 13:26:19 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 5FDA822D55 for ; Tue, 25 Aug 2020 13:26:19 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id UQ+ou5z8+NJt for ; Tue, 25 Aug 2020 13:26:18 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by silver.osuosl.org (Postfix) with ESMTPS id CE99F1FEAE for ; Tue, 25 Aug 2020 13:26:17 +0000 (UTC) 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-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: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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 Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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. _______________________________________________ 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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 213DFC433DF for ; Tue, 25 Aug 2020 13:26:30 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 E6F8820639 for ; Tue, 25 Aug 2020 13:26:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="qlRr2Rtw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E6F8820639 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Rbl63kZjMqbyHReKGxn4FUCm6Hsfsk7ZoFL8iLq7aZE=; b=qlRr2RtwEY6wTed7UnW3qMOFh 4166gydGTEZ7ZLPQyjE9MQHc6m6rilfAzNvRWD5mLCV/ww1BF6IuSqIa1A8OEBJm6pQ3/u2P9bPT3 J3tNLAPYrXv9q6/zUrNQFKLxYENIAcWfrqT/Tv7cmYEy5e7pg7ybX3JpujaHcmoeVlmxLwA0Z+BE5 xtIkF4IXM5yvg98mqdq4TapKqkDPJz0v+pxH+phk1m8xa55edB9EYQAG6L45aj76u+gYoLq6NqjMM Mgmgdme0bLmUjKIpIL9Idqlp9zi22kTXZ8Ft/HZpTCs+ZC5/WT0P7VjV1hbxPWuhSta3+RzGw6mIQ QdDs36pDQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kAYxy-0000dD-6i; Tue, 25 Aug 2020 13:26:22 +0000 Received: from verein.lst.de ([213.95.11.211]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kAYxs-0000b7-BS; Tue, 25 Aug 2020 13:26:17 +0000 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-Disposition: inline In-Reply-To: <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200825_092616_548520_135CD347 X-CRM114-Status: GOOD ( 11.14 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org 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. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: a saner API for allocating DMA addressable pages Date: Tue, 25 Aug 2020 15:26:12 +0200 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 Return-path: Content-Disposition: inline In-Reply-To: <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> Sender: linux-doc-owner@vger.kernel.org To: Marek Szyprowski Cc: Christoph Hellwig , Mauro Carvalho Chehab , Thomas Bogendoerfer , "James E.J. Bottomley" , Joonyoung Shim , Seung-Woo Kim , Kyungmin Park , Ben Skeggs , Pawel Osciak , Matt Porter , iommu@lists.linux-foundation.org, Tom Lendacky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org, nouveau@lists.freedesktop. List-Id: nouveau.vger.kernel.org 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. 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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 56129C433E1 for ; Tue, 25 Aug 2020 13:27:41 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 17D952071E for ; Tue, 25 Aug 2020 13:27:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ht/DEU3z" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17D952071E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iVW4XorMsJ/KkyV97hxfoajBRv8lH/CaPFpI5jc30Cg=; b=ht/DEU3zGppd4LyvPP5OMYbH4 Y+uztiFCYCDOl1IF1aQXImFOuBT0uhxKDXVtCd0404m8koBkg6Eby+rRtrZa+5LNDDm4EmHjWWL5R gFT9Vy6FH51rcxYH7bxQvo1f5if5th5Fk30iLj6zgKwHnog/vKIo39gZAJZ9AoBTbicFEfjTMPf+U zgPgjyEjc6otkInAnTY0rqeonfeXbVg76ld/WcP7L7AOr8pN9RifpNSpZzokJ8zlV/+AGvKTgW9OW 2BzRGfoMyArMUjXFXGIuTsQs6x4nQAV/hYWOiMzPtgLh8j/z9hTZxGueVRJ4b+Sf0Gw+Fbo9JXU24 Q18RZzQxw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kAYxv-0000cS-RC; Tue, 25 Aug 2020 13:26:19 +0000 Received: from verein.lst.de ([213.95.11.211]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kAYxs-0000b7-BS; Tue, 25 Aug 2020 13:26:17 +0000 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-Disposition: inline In-Reply-To: <8fa1ce36-c783-1a02-6890-211eb504a33b@samsung.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200825_092616_548520_135CD347 X-CRM114-Status: GOOD ( 11.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel