Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756723AbaJXRDo (ORCPT ); Fri, 24 Oct 2014 13:03:44 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:42651 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755894AbaJXRDn (ORCPT ); Fri, 24 Oct 2014 13:03:43 -0400 X-IronPort-AV: E=Sophos;i="5.04,781,1406592000"; d="scan'208";a="185970812" Date: Fri, 24 Oct 2014 18:01:12 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Catalin Marinas CC: Stefano Stabellini , 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 In-Reply-To: <20141024154353.GE20534@e104818-lin.cambridge.arm.com> Message-ID: References: <1412941908-5850-3-git-send-email-stefano.stabellini@eu.citrix.com> <20141010120702.GI7755@arm.com> <20141013125725.GA19156@arm.com> <20141024104746.GC1955@localhost> <20141024154353.GE20534@e104818-lin.cambridge.arm.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 24 Oct 2014, Catalin Marinas wrote: > 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 This is probably the cleanest option. I am going to send it out and see what the comments are. I might still be able to request a backport if it doesn't make 3.18. > > 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/