Re: [PATCH] powerpc/pci: fix PCI-e devices rescan issue on powerpc platform

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On 04/10/2013 05:08 PM, Chen Yuanquan-B41889 wrote:
On 04/03/2013 12:08 PM, Chen Yuanquan-B41889 wrote:
On 04/02/2013 11:10 PM, Benjamin Herrenschmidt wrote:
On Tue, 2013-04-02 at 19:26 +0800, Yuanquan Chen wrote:
So we move the DMA & IRQ initialization code from pcibios_setup_devices() and construct a new function pcibios_enable_device. We call this function in pcibios_enable_device, which will be called by PCI-e rescan code. At the meanwhile, we avoid the the impact on cardbus. I also validate this patch with
silicon's PCIe-sata which encounters the IRQ issue.
My worry is that this delays the setup of the IRQ and DMA to very late in
the process, possibly after the quirks have been run, which can be
problematic. We have platform hooks that might try to "fixup" specific
IRQ issues on some platforms (especially macs) which I worry might fail
if delayed that way (I may be wrong, I don't have a specific case in mind,
but I would feel better if we kept setting up these things earlier).

Cheers,
Ben.


Hi Ben,

I have checked all the quirk functions which are declared in kernel arch/powerpc
with command :
grep DECLARE_PCI_FIXUP_ `find arch/powerpc/ *.[hc]`

All the quirk function are defined as DECLARE_PCI_FIXUP_EARLY , DECLARE_PCI_FIXUP_HEADER and DECLARE_PCI_FIXUP_FINAL, except quirk_uli5229() in arch/powerpc/platforms/fsl_uli1575.c, which is defined both as DECLARE_PCI_FIXUP_HEADER and DECLARE_PCI_FIXUP_RESUME. So the quirk_uli5229() will also be called with PCI pm module. The quirk functions defined as xxx_FINAL, HEADER and EARLY,
will be called in the path:

pci_scan_child_bus()->pci_scan_slot()->pci_scan_single_device()->pci_scan_device()->pci_setup_device()
->pci_device_add()

the pci_scan_slot() is called earlier than pcibios_fixup_bus() even for the first scan of PCI-e bus, so the quirk functions on powerpc platform is called before the DMA & IRQ fixup. So in reality, the delay of DMA & IRQ fixup
won't affect anything.

Regards,
Yuanquan


Hi Ben,

How do you think about this? Do you have any comment?

Thanks,
Yuanquan


Hi Bjorn,

There's no response from Ben. How do you think about this patch? What's your advice?

Thanks,
Yuanquan










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