On Thu, Jul 25, 2013 at 02:25:04PM -0400, Don Dutile wrote: > On 07/25/2013 01:19 PM, Bjorn Helgaas wrote: > >On Wed, Jul 24, 2013 at 04:42:03PM -0400, Don Dutile wrote: > >>On 07/23/2013 06:35 PM, Bjorn Helgaas wrote: > >>>On Thu, Jul 11, 2013 at 03:03:27PM -0600, Alex Williamson wrote: > >>>>+ * pcie_for_each_requester - Call callback @fn on each devices and DMA source > >>>>+ * from @requestee to the PCIe requester ID visible > >>>>+ * to @bridge. > >>> > >>>Transactions from a device may appear with one of several requester IDs, > >>>but there's not necessarily an actual pci_dev for each ID, so I think the > >>ditto above; have to have a pdev for each id.... > > > >This *might* be true, but I don't think we should rely on it. For > >example: > > > > 00:1c.0 PCIe to PCI bridge to [bus 01] > > 01:01.0 PCI endpoint > > > >The bridge will take ownership of DMA transactions from the 01:01.0 > >endpoint. An IOMMU on bus 00 will see a bridge-assigned requester > >ID of 01:00.0 (subordinate bus number, devfn zero), but there is no > >01:00.0 device. > > > Clarification: > I meant that each requester-id must have at least 1 PCI device associated > with it. I don't think that's true, as in the example above. Requester ID 0x0100 has no pci_dev associated with it. What am I missing? Maybe you mean that requester ID 0x0100 is associated with pci_dev 01:01.0 in the sense that DMAs from 01:01.0 appear with that ID? That's true, but I can't think of a reason why we would start with ID 0x0100 and try to look up 01:01.0 from it. And of course, if you *did* try to look up the device, there could be several of them. Bjorn -- 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
