Subject: Re: Problem with OF interrupt parsing code

From: Scott Wood <[email-masked]>
Date: Mon, 01 Oct 2007 16:26:14 -0500

Gerhard Pircher wrote:
> First some information about my target setup. I didn't specify an
> interrupt-map and interrupt-map-mask property in the pci node, because
> AFAIK there are three different AmigaOne models with different IRQ
> routing.

So detect which one you're running on in the bootwrapper, and fix up (or 
select) the device tree appropriately.

> Secondly the AmigaOne is a desktop system with 4 PCI/AGP slots,
> thus I can't specify device nodes for all possible devices. By looking at
> pci_read_irq_line() in pci_common.c it should be possible for the kernel
> to fall back to the interrupt settings in the PCI config space of every
> device.

Those interrupt settings are purely a communication vector from firmware 
to OS.  Is your firmware putting i8259 interrupt numbers in there, and 
did you set the default interrupt controller?

> The problem occurs now, if there is no device node defined for another
> PCI device. In this case, of_irq_map_pci() checks for an interrupt pin,
> searches again for the host bridge node and calls of_irq_map_raw() with
> the device node of the host bridge. The function finds the
> #interrupt-cells, #address-cells, interrupt-controller properties, but
> fails to find the interrupt-map property (because it's missing in the
> device tree). Therefore the function then tries to find a new parent,
> which leads to an endless loop (it always selects the PCI2ISA southbridge
> in the device tree).

That seems likely... there should probably be some loop detection.

-Scott