On Tue, Mar 28, 2017 at 12:27 AM, Oza Oza <oza.oza@xxxxxxxxxxxx> wrote: > On Mon, Mar 27, 2017 at 8:16 PM, Rob Herring <robh@xxxxxxxxxx> wrote: >> On Sat, Mar 25, 2017 at 12:31 AM, Oza Pawandeep <oza.oza@xxxxxxxxxxxx> wrote: >>> it is possible that PCI device supports 64-bit DMA addressing, >>> and thus it's driver sets device's dma_mask to DMA_BIT_MASK(64), >>> however PCI host bridge may have limitations on the inbound >>> transaction addressing. As an example, consider NVME SSD device >>> connected to iproc-PCIe controller. >>> >>> Currently, the IOMMU DMA ops only considers PCI device dma_mask >>> when allocating an IOVA. This is particularly problematic on >>> ARM/ARM64 SOCs where the IOMMU (i.e. SMMU) translates IOVA to >>> PA for in-bound transactions only after PCI Host has forwarded >>> these transactions on SOC IO bus. This means on such ARM/ARM64 >>> SOCs the IOVA of in-bound transactions has to honor the addressing >>> restrictions of the PCI Host. >>> >>> current pcie frmework and of framework integration assumes dma-ranges >>> in a way where memory-mapped devices define their dma-ranges. >>> dma-ranges: (child-bus-address, parent-bus-address, length). >>> >>> but iproc based SOCs and even Rcar based SOCs has PCI world dma-ranges. >>> dma-ranges = <0x43000000 0x00 0x00 0x00 0x00 0x80 0x00>; >> >> If you implement a common function, then I expect to see other users >> converted to use it. There's also PCI hosts in arch/powerpc that parse >> dma-ranges. > > the common function should be similar to what > of_pci_get_host_bridge_resources is doing right now. > it parses ranges property right now. > > the new function would look look following. > > of_pci_get_dma_ranges(struct device_node *dev, struct list_head *resources) > where resources would return the dma-ranges. > > but right now if you see the patch, of_dma_configure calls the new > function, which actually returns the largest possible size. > so this new function has to be generic in a way where other PCI hosts > can use it. but certainly iproc(Broadcom SOC) , rcar based SOCs can > use it for sure. > > although having powerpc using it; is a separate exercise, since I do > not have any access to other PCI hosts such as powerpc. but we can > workout with them on thsi forum if required. You don't need h/w. You can analyze what parts are common, write patches to convert to common implementation, and build test. The PPC and rcar folks can test on h/w. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
