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=-2.3 required=3.0 tests=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 4AD14C31E40 for ; Tue, 6 Aug 2019 05:14:43 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 B61F42147A for ; Tue, 6 Aug 2019 05:14:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B61F42147A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 462jVm2xyYzDqHw for ; Tue, 6 Aug 2019 15:14:40 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 462jSg0KgTzDqcQ for ; Tue, 6 Aug 2019 15:12:49 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id 8410D68B05; Tue, 6 Aug 2019 07:12:42 +0200 (CEST) Date: Tue, 6 Aug 2019 07:12:42 +0200 From: Christoph Hellwig To: Gavin Li Subject: Re: [PATCH 1/2] dma-mapping: fix page attributes for dma_mmap_* Message-ID: <20190806051242.GA13269@lst.de> References: <20190805080145.5694-1-hch@lst.de> <20190805080145.5694-2-hch@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) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Gavin Li , Shawn Anastasio , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Russell King , linux-mips@vger.kernel.org, Paul Burton , Catalin Marinas , James Hogan , Will Deacon , Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Robin Murphy Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Mon, Aug 05, 2019 at 07:55:44PM -0700, Gavin Li wrote: > > /* create a coherent mapping */ > > ret = dma_common_contiguous_remap(page, size, VM_USERMAP, > > - arch_dma_mmap_pgprot(dev, PAGE_KERNEL, attrs), > > + dma_pgprot(dev, PAGE_KERNEL, attrs), > > __builtin_return_address(0)); > > if (!ret) { > > __dma_direct_free_pages(dev, size, page); > > Is dma_common_contiguous_remap() still necessary in the > DMA_ATTR_NON_CONSISTENT case? I would presume it would be fine to just > return a linearly mapped address in that case. It would not be required for a real DMA_ATTR_NON_CONSISTENT implementation. But only parisc and mips actually properly implement DMA_ATTR_NON_CONSISTENT, everyone ignores it. Given that the API is a little ill defined and I have a better replacement in the pipeline I don't want to start implementing it for other architectures now.