Re: [PATCH 2/6] PCI/MSI: add hooks to populate the msi_domain field
From: Marc Zyngier
Date: Tue Dec 09 2014 - 07:13:11 EST
On 09/12/14 11:57, Yijing Wang wrote:
>>>> +void __weak pcibios_set_phb_msi_domain(struct pci_bus *bus)
>>>> +static void pci_set_bus_msi_domain(struct pci_bus *bus)
>>>> + struct pci_dev *bridge = bus->self;
>>>> + if (!bridge)
>>>> + pcibios_set_phb_msi_domain(bus);
>>>> + else
>>>> + dev_set_msi_domain(&bus->dev, dev_get_msi_domain(&bridge->dev));
>>> Hi Marc, we can not assume pci devices under same phb share the same msi irq domain,
>>> now in x86, pci devices under the same phb may associate different msi irq domain.
> Hi Marc,
>> Well, this is not supposed to be a perfect solution yet, but instead a
>> basis for discussion. What I'd like to find out is:
>> - What is the minimum granularity for associating a device with its MSI
>> domain in existing platforms?
> PCI device, after Gerry's msi irq domain patchset which now in linux-next,
> in x86, we will find msi irq domain by pci_dev.
Are you *really* associating the MSI domain on a per pci-device basis?
That is, you have devices on the same PCI bus talking to different MSI hw?
> I generally agree your first patch which associate basic device with msi irq domain.
>> - What topology data structures do you use to find out what MSI
>> controller a device should be matched with?
> Now only arm and arm64 use msi controller to setup/teardown msi irqs,
> in arm, now msi controller saved in pci_sys_data, and for arm64, it seems
> to be saved in pci_bus. For a more common method to find msi controller/irq domain,
> I prefer pci_dev/device.
Forget about msi_controller, the whole goal of this series is to make it
obsolete. On your x86 platform, what how do you identify which MSI
domain should be associated with a given PCI device? Surely you must
have a set of data structures or ACPI tables which give you that
>> - What in-tree platform already has this requirements?
> As mentioned above, x86 does.
Let me rephrase that in a non-ambiguous manner: can you point me to a
file implementing this in mainline?
Jazz is not dead. It just smells funny...
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