>>> +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
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