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_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 B65CEC282CE for ; Wed, 24 Apr 2019 19:27:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D7D52183E for ; Wed, 24 Apr 2019 19:27:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731527AbfDXT1M (ORCPT ); Wed, 24 Apr 2019 15:27:12 -0400 Received: from verein.lst.de ([213.95.11.211]:56600 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725946AbfDXT1M (ORCPT ); Wed, 24 Apr 2019 15:27:12 -0400 Received: by newverein.lst.de (Postfix, from userid 2407) id 253F368C4E; Wed, 24 Apr 2019 21:26:53 +0200 (CEST) Date: Wed, 24 Apr 2019 21:26:52 +0200 From: Christoph Hellwig To: Nicolin Chen Cc: Christoph Hellwig , robin.murphy@arm.com, vdumpa@nvidia.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will.deacon@arm.com, joro@8bytes.org, m.szyprowski@samsung.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, tony@atomide.com Subject: Re: [PATCH v2 RFC/RFT 1/5] ARM: dma-mapping: Add fallback normal page allocations Message-ID: <20190424192652.GA29032@lst.de> References: <20190326230131.16275-1-nicoleotsuka@gmail.com> <20190326230131.16275-2-nicoleotsuka@gmail.com> <20190424150638.GA22191@lst.de> <20190424183310.GA6168@Asurada-Nvidia.nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190424183310.GA6168@Asurada-Nvidia.nvidia.com> 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, Apr 24, 2019 at 11:33:11AM -0700, Nicolin Chen wrote: > I feel it's similar to my previous set, which did most of these > internally except the renaming part. But Catalin had a concern > that some platforms might have limits on CMA range [1]. Will it > be still okay to do the fallback internally? > > [1: https://www.spinics.net/lists/arm-kernel/msg714295.html ] Catalins statement is correct, but I don't see how it applies to your patch. Your patch just ensures that the fallback we have in most callers is uniformly applied everywhere. The non-iommu callers will still need to select a specific zone and/or retry just the page allocator with other flags if the CMA (or fallback) page doesn't match what they need. dma-direct does this correctly and I think the arm32 allocator does as well, although it is a bit hard to follow sometimes.