Re: [Bisected] [-next-20130204] usb/hcd: irq 18: nobody cared

From: Yinghai Lu
Date: Mon Feb 11 2013 - 19:08:58 EST

On Mon, Feb 11, 2013 at 2:41 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> [+cc linux-acpi, linux-pci]
> The _PRT describes motherboard interrupt wiring, which has nothing to
> do with PCI bus numbers. Our current drivers/acpi/pci_irq.c caches
> the PCI bus number along with the _PRT, and I think that's a mistake.
> The bus number binding means acpi_pci_irq_add_prt() has to happen
> after enumerating everything below a bridge, and it will prevent us
> from doing any bus number reassignment for hotplug.
> I think we should remove the bus numbers from the cached _PRT (or
> maybe even remove the _PRT caching completely). When we enable a PCI
> device's IRQ, we should search up the PCI device tree looking for a
> _PRT associated with each node, and applying normal PCI bridge
> swizzling when we don't find a _PRT. I think this can be done without
> using PCI bus numbers at all.

Agreed, will give it try to remove the _PRT caching completely.


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