quoted

quoted

+static void pci_set_msi_domain(struct pci_dev *dev)
+{
+	/*
+	 * If no domain has been set through the pcibios callback,
+	 * inherit the default from the bus device.
+	 */
+	if (!dev_get_msi_domain(&dev->dev))
+		dev_set_msi_domain(&dev->dev,
+				   dev_get_msi_domain(&dev->bus->dev));
+}

Hi Marc, now we have two ways to associate the pci_dev and msi_domain, right ?

1. associate pci_dev and msi_domain in pcibios_add_device() like x86.

2. Inherit msi_domain from pci_dev->bus.

My question is if all pci devices inherit msi_domain from the pci_bus,
so all pci devices under same pci host bridge have the same msi_domain assigned by
weak pcibios_set_phb_msi_domain(). So why not save the pci host bridge specific
msi_domain in pci_host_bridge. Then pci devices could inherit the msi_domain from
its pci host bridge directly, no need to involve pci bus in the assignment.

But then, you would end-up maintaining another msi_domain field inside
the pci_host bridge structure. What do you gain by doing so?

My original thought is holding msi_domain field inside the pci_host_bridge is
more simple than every bus maintaining the msi_domain, but this proposal has a
disadvantage that sometimes we must setup for every device. I checked x86 DMAR code,
and found most DMAR would report PCIe root port device associating the msi_domain, not the EP device.
So pcibios_add_device could only associate these bridge device msi_domain, and its children
devices will propagate from their parent bus(get msi_domain from its bridge).

So now I agree your idea, please forgive my nagging :)

Thanks!
Yijing.

With this series, msi_domain has the nice property of always being tied
to a device (and struct pci_bus always has a device). We always have
phb->bus->dev.msi_domain within reach, and architecture code can decide
to override it on a per-device basis.

What else do you need? What am I missing from your proposal?

Thanks,

	M.

-- 
Thanks!
Yijing