On Wed, Nov 04, 2015 at 03:19:13PM +0000, Phil Edworthy wrote: > On 04 November 2015 15:02, Liviu wrote: > > On Wed, Nov 04, 2015 at 02:48:38PM +0000, Phil Edworthy wrote: > > > Sure, though since this is bog standard Intel PCIe ethernet card which works > > > fine when the IOMMU is effectively unused, I don’t think there is a problem > > > with that. > > > > > > The driver for the PCIe controller sets up the IOMMU mapping ok when I > > > do a test call to dma_alloc_coherent() in the controller's driver. i.e. when I > > > do this, it ends up in arm_iommu_alloc_attrs(), which calls > > > __iommu_alloc_buffer() and __alloc_iova(). > > > > > > When an endpoint driver allocates and maps a dma coherent buffer it > > > also needs to end up in arm_iommu_alloc_attrs(), but it doesn't. > > > > Why do you think that? Remember that the only thing attached to the IOMMU is > > the > > host controller. The endpoint is on the PCIe bus, which gets a different > > translation > > that the IOMMU knows nothing about. If it helps you to visualise it better, think > > of the host controller as another IOMMU device. It's the ops of the host > > controller > > that should be invoked, not the IOMMU's. > Ok, that makes sense. I'll have a think and poke it a bit more... Take a look at of_iommu_configure, which is currently lacking support for PCI devices. It should be using a variant on the device-tree bindings already in use for describing MSI device IDs, so that we can translate the RequesterID of the endpoint into an ID that the IOMMU can understand. Will -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
