On Wednesday 17 December 2014 18:24:43 Murali Karicheri wrote:
> On 12/17/2014 04:56 PM, Arnd Bergmann wrote:
> > On Wednesday 17 December 2014 13:02:23 Murali Karicheri wrote:
> >
> > What's wrong with using arch_setup_dma_ops() from PCI as suggested
> > previously?
> >
+Will Deacon
> I had originally written a code based on that line as below. But
> dma-ranges property is also used by ppc and other architectures in the
> pci device DT node. So I wasn't sure how this code impact PCI driver
> functionality on those platforms. Hence used a simpler change as all
> that is needed for keystone is to get the dma_pfn_offset rightly set in
> the pci slave device.
But in your patch, you don't call arch_setup_dma_ops() at all.
> Initially I had a function implemented as below for this in of_pci.c.
>
> + * of_pci_dma_configure - Setup DMA configuration for a pci device
> + * @dev: pci device to apply DMA configuration
> + *
> + * Try to get devices's DMA configuration from DT and update it
> + * accordingly. This is a similar to of_dma_configure() for platform
> + * devices.
> + *
> + */
> +void of_pci_dma_configure(struct pci_dev *dev)
> +{
> + struct device *host_bridge, *parent;
> + struct pci_bus *bus = dev->bus;
> + u64 dma_addr, paddr, size;
> + int ret;
> +
> + while (!pci_is_root_bus(bus))
> + bus = bus->parent;
> + host_bridge = bus->bridge;
> +
> + parent = host_bridge->parent;
> + if (parent->of_node) {
so far it looks good, although we may want to introduce
a helper function to get the of_node.
> + /*
> + * if dma-coherent property exist, call arch hook to setup
> + * dma coherent operations.
> + */
> + if (of_dma_is_coherent(parent->of_node)) {
> + set_arch_dma_coherent_ops(&dev->dev);
> + dev_info(&dev->dev, "device is dma coherent\n");
> + }
set_arch_dma_coherent_ops no longer exists. Just keep the flag in a
local variable
> + /*
> + * if dma-ranges property doesn't exist - just return else
> + * setup the dma offset
> + */
> + ret = of_dma_get_range(parent->of_node, &dma_addr,
> &paddr, &size);
> + if (ret < 0) {
> + dev_info(&dev->dev, "no dma range information to
> setup\n");
> + printk("no dma range information to setup\n");
> + return;
> + }
> +
> + /* DMA ranges found. Calculate and set dma_pfn_offset */
> + dev->dev.dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
> + dev_info(&dev->dev, "dma_pfn_offset(%#08lx)\n",
> dev->dev.dma_pfn_offset);
Same for the offset and size here, then pass all of the above into
arch_setup_dma_ops. This is also where we need to hook up the iommu
support once we decide how to make that work with the ARM SMMU.
Will, I think we may have a problem on ARM64 now, since we only replaced
set_arch_dma_coherent_ops on ARM32 but not ARM64. Can you send a fix for
this? Without that, we don't have any coherent operations on ARM64 any
more, unless I'm missing something.
Arnd
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