On Tuesday 06 May 2014 16:48:33 Bjorn Helgaas wrote: > @@ -51,8 +53,12 @@ static void gapspci_fixup_resources(struct pci_dev *dev) > /* > * Redirect dma memory allocations to special memory window. > */ > + region.start = GAPSPCI_DMA_BASE; > + region.end = GAPSPCI_DMA_BASE + GAPSPCI_DMA_SIZE - 1; > + res.flags = IORESOURCE_MEM; > + pcibios_bus_to_resource(dev->bus, &res, ®ion); > BUG_ON(!dma_declare_coherent_memory(&dev->dev, > - GAPSPCI_DMA_BASE, > + res->start, > GAPSPCI_DMA_BASE, > GAPSPCI_DMA_SIZE, > DMA_MEMORY_MAP | Not sure if this is an improvement. I understand the intention, but it's actually possible for the offset to be different both ways: Your patch applies the outbound mem_offset that was provided when registering the MMIO resource for the PCI host bridge. What the driver needs instead is the inbound DMA offset that gets applied by some host bridges that don't have a 1:1 mapping but also don't have an IOMMU. We know that on this particular platform, both are zero, so the original code works and it will keep working with your change, but I think it's a mistake anyway. I have seen both kinds of offsets in the past on real machines, but I am not aware of any where they are both nonzero and have the same value. Arnd -- 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
