From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754170AbcEPP0K (ORCPT ); Mon, 16 May 2016 11:26:10 -0400 Received: from mail-lb0-f179.google.com ([209.85.217.179]:34619 "EHLO mail-lb0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754107AbcEPP0I (ORCPT ); Mon, 16 May 2016 11:26:08 -0400 Subject: Re: [RFC PATCH 09/11] drivers: acpi: implement acpi_dma_configure To: Robin Murphy , Timur Tabi , Lorenzo Pieralisi References: <1460654743-7896-1-git-send-email-lorenzo.pieralisi@arm.com> <1460654743-7896-10-git-send-email-lorenzo.pieralisi@arm.com> <5714BA5A.2040008@arm.com> <5739E416.6000501@semihalf.com> Cc: "linux-arm-kernel@lists.infradead.org" , vikrams@codeaurora.org, Marc Zyngier , "Rafael J. Wysocki" , lkml , Will Deacon , Sinan Kaya , linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org, Hanjun Guo , linux-pci@vger.kernel.org, Bjorn Helgaas , Jon Masters From: Tomasz Nowicki Message-ID: <5739E68B.2080907@semihalf.com> Date: Mon, 16 May 2016 17:26:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <5739E416.6000501@semihalf.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.05.2016 17:15, Tomasz Nowicki wrote: > On 18.04.2016 12:43, Robin Murphy wrote: >> On 15/04/16 19:29, Timur Tabi wrote: >>> On Thu, Apr 14, 2016 at 12:25 PM, Lorenzo Pieralisi >>> wrote: >>>> +void acpi_dma_configure(struct device *dev, enum dev_dma_attr attr) >>>> +{ >>>> + struct iommu_ops *iommu; >>>> + >>>> + iommu = iort_iommu_configure(dev); >>>> + >>>> + /* >>>> + * Assume dma valid range starts at 0 and covers the whole >>>> + * coherent_dma_mask. >>>> + */ >>>> + arch_setup_dma_ops(dev, 0, dev->coherent_dma_mask + 1, iommu, >>>> + attr == DEV_DMA_COHERENT); >>>> +} >>> >>> I have a network driver that is impacted by this code, so thank you >>> for posting this. (See >>> https://www.mail-archive.com/netdev@vger.kernel.org/msg106249.html). >>> >>> One one SOC, the driver needs to set the mask to 32 bits. On another >>> SOC, it needs to set it to 64 bits. On device tree, the driver will >>> use dma-ranges. >> >> That's the wrong way to look at it - the driver isn't _using_ >> dma-ranges, you're merely relying on the OF code setting the _default_ >> DMA mask differently based on the property. If your driver is in the >> minority of those which actually care about DMA masks, then it should be >> calling dma_set_mask_and_coherent() appropriately and not relying on the >> default. > > I don't see the clear strategy for setting DMA mask as well. > > Lets consider DT boot method example: > 1. SMMUv2 supports 48bit translation and 1:1 address map > dma-ranges = <0x0 0x0 0x0 0x0 0x00010000 0x0>; > and we are adding PCI device: > > pci_device_add -> DMA_BIT_MASK(32) by default > pci_dma_configure > of_dma_configure -> reads dma-ranges and calculates 48bit DMA mask, > but it picks minimum, we stay with DMA_BIT_MASK(32) > > now PCI dev turns out to be e1000e NIC: > e1000_probe > dma_set_mask_and_coherent -> tries to set DMA_BIT_MASK(64) > dma_set_mask -> there is no set_dma_mask ops for SMMUv2 so we let Sorry, there is no .set_dma_mask ops for ARM64 (not SMMUv2) Tomasz