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=-2.2 required=3.0 tests=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 C4764C4CECE for ; Mon, 14 Oct 2019 14:05:26 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 90FCB2083B for ; Mon, 14 Oct 2019 14:05:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90FCB2083B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id D0E78142E; Mon, 14 Oct 2019 14:05:25 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 59CCB1389 for ; Mon, 14 Oct 2019 13:55:01 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id E74FC5D3 for ; Mon, 14 Oct 2019 13:55:00 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0982A337; Mon, 14 Oct 2019 06:55:00 -0700 (PDT) Received: from [10.1.197.57] (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 224D83F68E; Mon, 14 Oct 2019 06:54:59 -0700 (PDT) Subject: Re: [BUG] dma-ranges, reserved memory regions, dma_alloc_coherent: possible bug? To: Daniele Alessandrelli , Christoph Hellwig , Marek Szyprowski , Vladimir Murzin References: From: Robin Murphy Message-ID: Date: Mon, 14 Oct 2019 14:54:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB Cc: iommu@lists.linux-foundation.org, Arnd Bergmann X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On 13/10/2019 15:28, Daniele Alessandrelli wrote: > Hi, > > It looks like dma_alloc_coherent() is setting the dma_handle output > parameter to the memory physical address and not the device bus > address when the device is using reserved memory regions for DMA > allocation. This is despite using 'dma_ranges' in the device tree to > describe the DMA memory mapping. Is this expected behavior or a bug? That does sound like a bug :( > Here is a reduced version of the device tree I'm using: > \ { > reserved-memory { > #address-cells = <2>; > #size-cells = <2>; > ranges; > mydev_rsvd: rsvd_mem@494800000 { > compatible = "shared-dma-pool"; > reg = <0x4 0x94800000 0x0 0x200000>; > no-map; > }; > }; > soc { > compatible = "simple-bus"; > #address-cells = <2>; > #size-cells = <2>; > ranges; > dma_ranges; > > mybus { > ranges = <>; > dma-ranges = <>; > compatible = "simple-bus"; > #address-cells = <2>; > #size-cells = <2>; > ranges = <0x0 0x0 0x0 0x0 0x0 0x80000000>; > dma-ranges = <0x0 0x80000000 0x4 0x80000000 > 0x0 0x80000000>; > > mydevice { > compatible = "my-compatible-string"; > memory-region = <&mydev_rsvd>; > } > } > } > }; > > It looks like this issue was previously fixed by commit c41f9ea998f3 > ("drivers: dma-coherent: Account dma_pfn_offset when used with device > tree") which introduced a new function ('dma_get_device_base()') to > return the reserved memory address as seen by the device. However, > such a function, even if still there, is not used anymore in latest > code (as of v5.4-rc2). Was that done for a specific reason? Or is it > just a mistake? Hmm, it looks like 43fc509c3efb ("dma-coherent: introduce interface for default DMA pool") removed the caller of dma_get_device_base() in the alloc path shortly after it was introduced, which certainly appears as if it may have been unintentional - Vladimir? Robin. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu