[PATCH v5 9/9] PCI: xgene: Use pci_scan_root_bus_msi()

[Duc Dang]

On Mon, Aug 10, 2015 at 3:04 PM, Bjorn Helgaas <bhelgaas at google.com> wrote:
> Hi Marc,
>
> On Thu, Aug 06, 2015 at 04:26:10PM +0100, Marc Zyngier wrote:
>> On 04/08/15 22:54, Bjorn Helgaas wrote:
>> > Previously there was no way to specify the MSI controller when creating a
>> > new PCI root bus, so we had to create the bus, set its MSI controller, then
>> > scan the bus.  With the new pci_scan_root_bus_msi() interface, we can
>> > specify the MSI controller up front and get rid of that intermediate step.
>> >
>> > Look up the MSI controller first, then use pci_scan_root_bus_msi() to
>> > create and scan the root PCI bus.
>>
>> I'm wondering about these XGene patches.
>>
>> With the code that is queued for v4.3 in tip/irq/core, the X-Gene MSI
>> driver doesn't export a struct msi_controller anymore, and entirely
>> relies on IRQ domains to identify to be matched with the actual PCI driver.
>>
>> Do you intend this as a cleanup until everything lands in mainline? At
>> that point, we'd be able to remove all traces of struct msi_controller
>> from this driver.
>
> I haven't been following the IRQ domain stuff or tip/irq/core, so I
> really don't know how this relates to that.  I took a look, and I see
> 8d63bc7beaee ("PCI/MSI: pci-xgene-msi: Get rid of struct
> msi_controller"), which removes an msi_controller pointer from
> pci-xgene-msi.c, but I don't see any pci-xgene.c changes in
> tip/irq/core.
>
> Are you saying that xgene_pcie_msi_enable() will go away eventually?
> And the OF "msi-parent" lookup will go away, or at least be moved
> elsewhere?  We currently have:
>
>   xgene_pcie_probe_bridge(...)
>   {
>     ...
>     bus = pci_create_root_bus(...);
>     xgene_pcie_msi_enable(...);
>     pci_scan_child_bus(bus);
>     ...
>   }
>
> I'd like to get rid of that arch-specific MSI enable stuff because
> then we can use a higher level interface, e.g., pci_scan_root_bus(),
> and make the X-Gene code slightly simpler.
>
>> Alternatively, we could ask tglx to add an extra patch to the existing
>> queue in order to clean up pci-xgene.c (nuking the whole
>> xgene_pcie_msi_enable function).
>
> Ah, I guess you *are* saying that xgene_pcie_msi_enable() will go away
> eventually.  I don't know how to do that, but apparently you do, so
> I'll just drop these X-Gene-related patches for now.

Hi Bjorn,

I tested PCIe MSI with Marc's patch on X-Gene platform and it was working fine.
xgene_pcie_msi_enable will go away. I will post clean up patch to
remove these msi_controller traces
for X-Gene.

>
> Bjorn



-- 
Regards,
Duc Dang.