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SubjectRe: [PATCH 3/5] PCI: Set PCI_BUS_FLAGS_MSI_REMAP if MSI controller supports IRQ remapping
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On 2016/5/25 5:04, Bjorn Helgaas wrote:

> On Wed, Apr 27, 2016 at 08:43:28PM +0800, Yongji Xie wrote:
>> On ARM HW the capability of IRQ remapping is abstracted on
>> MSI controller side. MSI_FLAG_IRQ_REMAPPING is used to advertise
>> this [1].
>>
>> To have a universal flag to test this capability for different
>> archs on PCI side, we set PCI_BUS_FLAGS_MSI_REMAP for PCI buses
>> when MSI_FLAG_IRQ_REMAPPING is set.
>>
>> [1] http://www.spinics.net/lists/kvm/msg130256.html
>>
>> Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com>
>> ---
>> drivers/pci/msi.c | 12 ++++++++++++
>> drivers/pci/probe.c | 3 +++
>> include/linux/msi.h | 6 +++++-
>> 3 files changed, 20 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
>> index a080f44..1661cdf 100644
>> --- a/drivers/pci/msi.c
>> +++ b/drivers/pci/msi.c
>> @@ -1134,6 +1134,18 @@ void *msi_desc_to_pci_sysdata(struct msi_desc *desc)
>> }
>> EXPORT_SYMBOL_GPL(msi_desc_to_pci_sysdata);
>>
>> +void pci_bus_check_msi_remapping(struct pci_bus *bus,
>> + struct irq_domain *domain)
>> +{
>> +#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
>> + struct msi_domain_info *info;
>> +
>> + info = msi_get_domain_info(domain);
>> + if (info->flags & MSI_FLAG_IRQ_REMAPPING)
>> + bus->bus_flags |= PCI_BUS_FLAGS_MSI_REMAP;
>> +#endif
>> +}
> Functions named "check_foo" are a pet peeve of mine because the name
> doesn't tell us anything about what the function *does*. In this
> case, we know it checks something about MSI remapping, but we don't
> know whether we're checking whether it's enabled, disabled, or some
> other property.
>
> I'd prefer something like:
>
> int pci_bus_msi_isolated(struct pci_bus *bus, struct irq_domain *domain)
> {
> struct msi_domain_info *info;
>
> if (!domain)
> return 0;
>
> info = msi_get_domain_info(domain);
> if (info->flags & MSI_FLAG_IRQ_REMAPPING)
> return 1;
>
> return 0;
> }
>
> void pci_set_bus_msi_domain(struct pci_bus *bus)
> {
> ...
> if (b == bus && pci_bus_msi_isolated(bus, d))
> bus->bus_flags |= PCI_BUS_FLAGS_MSI_REMAP;

Yes. This looks more reasonable. Thank you!

Regards,
Yongji

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