On Tue, Mar 28, 2017 at 7:43 PM, Rob Herring <robh@xxxxxxxxxx> wrote: > 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 Hi Rob, I have addressed your comment and made generic function. Gentle request to have a look at following approach and patch. [RFC PATCH 2/2] of/pci: call pci specific dma-ranges instead of memory-mapped. [RFC PATCH 1/2] of/pci: implement inbound dma-ranges for PCI I have tested this on our platform, with and without iommu, and seems to work. let me know your view on this. Regards, Oza.
