Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932783AbaJXPoN (ORCPT ); Fri, 24 Oct 2014 11:44:13 -0400 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:48320 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752465AbaJXPoJ (ORCPT ); Fri, 24 Oct 2014 11:44:09 -0400 Date: Fri, 24 Oct 2014 16:43:54 +0100 From: Catalin Marinas To: Stefano Stabellini Cc: Will Deacon , "xen-devel@lists.xensource.com" , "konrad.wilk@oracle.com" , "Ian.Campbell@citrix.com" , "david.vrabel@citrix.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux@arm.linux.org.uk" Subject: Re: [PATCH v4 3/7] [RFC] arm/arm64: introduce is_dma_coherent Message-ID: <20141024154353.GE20534@e104818-lin.cambridge.arm.com> References: <1412941908-5850-3-git-send-email-stefano.stabellini@eu.citrix.com> <20141010120702.GI7755@arm.com> <20141013125725.GA19156@arm.com> <20141024104746.GC1955@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 24, 2014 at 12:39:59PM +0100, Stefano Stabellini wrote: > On Fri, 24 Oct 2014, Catalin Marinas wrote: > > I think a better way would be some Xen hook around > > set_arch_dma_coherent_ops(). Does Xen have its own device tracking > > structures? If not, you may be able to add another bitfield to the > > kernel one. > > We don't have an additional device tracking struct on Xen. > I agree that a new bit somewhere would be the best solution, but I am > not sure where. Maybe in dev_archdata under arm and arm64? After all it > is already used to keep pointers to dma and coherency related > structures. I was thinking about something like below (maybe with some additional ARCH_HAS_NONCOHERENT_DMA config for architectures that are always coherent): diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 3b64d0bf5bba..ae399ccbd569 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -183,6 +183,7 @@ static void of_dma_configure(struct device *dev) * dma coherent operations. */ if (of_dma_is_coherent(dev->of_node)) { + dev->dma_coherent = 1; set_arch_dma_coherent_ops(dev); dev_dbg(dev, "device is dma coherent\n"); } diff --git a/include/linux/device.h b/include/linux/device.h index ce1f21608b16..e00ca876db01 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -796,6 +796,7 @@ struct device { bool offline_disabled:1; bool offline:1; + bool dma_coherent:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index d5d388160f42..9c9ba5a5428e 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -78,6 +78,11 @@ static inline int is_device_dma_capable(struct device *dev) return dev->dma_mask != NULL && *dev->dma_mask != DMA_MASK_NONE; } +static inline int is_device_dma_coherent(struct device *dev) +{ + return dev->dma_coherent; +} + #ifdef CONFIG_HAS_DMA #include #else > However given the timing constraints I hope you would be OK with the > suboptimal solution for now and create a common is_dma_coherent function > in 3.19? If you want to push something for 3.18, you could have a temporary solution but I would prefer a bool or something in the dev_archdata structure. Another untested patch: diff --git a/arch/arm64/include/asm/device.h b/arch/arm64/include/asm/device.h index cf98b362094b..243ef256b8c9 100644 --- a/arch/arm64/include/asm/device.h +++ b/arch/arm64/include/asm/device.h @@ -21,6 +21,7 @@ struct dev_archdata { #ifdef CONFIG_IOMMU_API void *iommu; /* private IOMMU data */ #endif + bool dma_coherent; }; struct pdev_archdata { diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h index adeae3f6f0fc..b6bc4c268878 100644 --- a/arch/arm64/include/asm/dma-mapping.h +++ b/arch/arm64/include/asm/dma-mapping.h @@ -54,11 +54,17 @@ static inline void set_dma_ops(struct device *dev, struct dma_map_ops *ops) static inline int set_arch_dma_coherent_ops(struct device *dev) { + dev->dev_archdata.dma_coherent = true; set_dma_ops(dev, &coherent_swiotlb_dma_ops); return 0; } #define set_arch_dma_coherent_ops set_arch_dma_coherent_ops +static inline int is_device_dma_coherent(struct device *dev) +{ + return dev->dev_archdata.dma_coherent; +} + #include static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr) This way you don't have to test for swiotlb vs iommu ops (we don't have the latter yet on arm64 but they are coming). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/