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=-5.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C8062C432C0 for ; Thu, 21 Nov 2019 15:25:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 9E49220674 for ; Thu, 21 Nov 2019 15:25:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="lcgnVmcM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E49220674 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+infradead-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=bombadil.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=e34fKbdjyJqE8wZ1dvzqwyTTWS35B0f86Ib/lcIwzaM=; b=lcgnVmcMXpK2iH giLDGnBij7KYB1idkudSdtiXcgEbftIJJ62Tm5qfu8CP2+Ho32R42lPmrRNo7c1RFA40C4Vpv0RRJ 6FVkBv4QaF2J76SPdAPNXTONFNCCxsqx9bH2SE9biVKeEHorT8yqbayxmaZsfxuY/T2A8ndGGmScN rSRDsxAosgupQ5GQdiog58863z7FuJMCjoekmB3VxTUpBqFaZ1HHzCFkMLJOaD4M/waDNGzRnTE/3 zQL/ZKAjZy1lfyxZjP0+8kAm/nQ5sVLOzd/t/AEGXA1m8ybCPx591W8txM90QyAskOyX3nIXo0KCY SXVdw3zO6WQN0s083rMg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXoKW-0005iI-IJ; Thu, 21 Nov 2019 15:25:12 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXoKS-0004XW-Gg for linux-arm-kernel@lists.infradead.org; Thu, 21 Nov 2019 15:25:10 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id B377668C4E; Thu, 21 Nov 2019 16:24:57 +0100 (CET) Date: Thu, 21 Nov 2019 16:24:57 +0100 From: Christoph Hellwig To: Nicolas Saenz Julienne Subject: Re: [PATCH v2] dma-mapping: treat dev->bus_dma_mask as a DMA limit Message-ID: <20191121152457.GA525@lst.de> References: <20191121092646.8449-1-nsaenzjulienne@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191121092646.8449-1-nsaenzjulienne@suse.de> 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-20191121_072508_723873_2B872BB5 X-CRM114-Status: GOOD ( 14.35 ) 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: Peter Zijlstra , Benjamin Herrenschmidt , Dave Hansen , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, Paul Mackerras , Hanjun Guo , Frank Rowand , Christoph Hellwig , Marek Szyprowski , Lorenzo Pieralisi , "H. Peter Anvin" , Paul Burton , Michael Ellerman , Joerg Roedel , x86@kernel.org, linux-acpi@vger.kernel.org, Ingo Molnar , James Hogan , Len Brown , devicetree@vger.kernel.org, Rob Herring , Borislav Petkov , Andy Lutomirski , Bjorn Helgaas , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Jens Axboe , linuxppc-dev@lists.ozlabs.org, "Rafael J. Wysocki" , linux-mips@vger.kernel.org, Ralf Baechle , iommu@lists.linux-foundation.org, Sudeep Holla , Robin Murphy Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 21, 2019 at 10:26:44AM +0100, Nicolas Saenz Julienne wrote: > Using a mask to represent bus DMA constraints has a set of limitations. > The biggest one being it can only hold a power of two (minus one). The > DMA mapping code is already aware of this and treats dev->bus_dma_mask > as a limit. This quirk is already used by some architectures although > still rare. > > With the introduction of the Raspberry Pi 4 we've found a new contender > for the use of bus DMA limits, as its PCIe bus can only address the > lower 3GB of memory (of a total of 4GB). This is impossible to represent > with a mask. To make things worse the device-tree code rounds non power > of two bus DMA limits to the next power of two, which is unacceptable in > this case. > > In the light of this, rename dev->bus_dma_mask to dev->bus_dma_limit all > over the tree and treat it as such. Note that dev->bus_dma_limit should > contain the higher accesible DMA address. > > Signed-off-by: Nicolas Saenz Julienne I've tentatively added this patch to the dma-mapping tree based on Robins principal approval of the last version. That way tomorrows linux-next run should still pick it up. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel