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From: Marc Zyngier <marc.zyngier@arm.com>
To: Yijing Wang <wangyijing@huawei.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jiang Liu <jiang.liu@linux.intel.com>
Cc: "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Will Deacon <Will.Deacon@arm.com>,
	"suravee.suthikulpanit@amd.com" <suravee.suthikulpanit@amd.com>
Subject: Re: [PATCH 2/6] PCI/MSI: add hooks to populate the msi_domain field
Date: Tue, 09 Dec 2014 12:12:55 +0000	[thread overview]
Message-ID: <5486E747.4010804@arm.com> (raw)
In-Reply-To: <5486E3BF.70703@huawei.com>

Yijing,

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
information.

>> - 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?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2014-12-09 12:13 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-12-08 20:12 [PATCH 0/6] Introducing per-device MSI domain Marc Zyngier
2014-12-08 20:12 ` [PATCH 1/6] device core: Introduce per-device MSI domain pointer Marc Zyngier
2014-12-08 20:12 ` [PATCH 2/6] PCI/MSI: add hooks to populate the msi_domain field Marc Zyngier
2014-12-09  2:03   ` Yijing Wang
2014-12-09 10:02     ` Marc Zyngier
2014-12-09 11:57       ` Yijing Wang
2014-12-09 12:12         ` Marc Zyngier [this message]
2014-12-09 12:24           ` Yijing Wang
2014-12-09 12:47           ` Jiang Liu
2014-12-09 14:03             ` Marc Zyngier
2014-12-09 14:11               ` Jiang Liu
2014-12-09 14:27                 ` Marc Zyngier
2014-12-09 14:35                   ` Jiang Liu
2014-12-09 14:59                     ` Marc Zyngier
2014-12-09 15:42                       ` Jiang Liu
2014-12-09 12:57   ` Jiang Liu
2015-01-27  0:40   ` Bjorn Helgaas
2015-01-27  0:43     ` Bjorn Helgaas
2014-12-08 20:12 ` [PATCH 3/6] PCI/MSI: of: add support for OF-provided msi_domain Marc Zyngier
2015-01-27  0:41   ` Bjorn Helgaas
2014-12-08 20:12 ` [PATCH 4/6] PCI/MSI: Let pci_msi_get_domain use struct device's msi_domain Marc Zyngier
2014-12-08 20:12 ` [PATCH 5/6] irqchip: GICv2m: Get rid of struct msi_controller Marc Zyngier
2014-12-08 20:12 ` [PATCH 6/6] irqchip: gicv3-its: " Marc Zyngier

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