How do external irq's get mapped?

[Zhang Wei-r63237]

Hi, Charles,

Maybe you can try my patches about showing irq-mapping relationship.

http://patchwork.ozlabs.org/linuxppc/patch?id=9999
http://patchwork.ozlabs.org/linuxppc/patch?id=9997
http://patchwork.ozlabs.org/linuxppc/patch?id=9998
http://patchwork.ozlabs.org/linuxppc/patch?id=9996

Hope it could help you.

Best Regards,
Zhang Wei

> Subject: RE: How do external irq's get mapped?
> 
> > 3. The offset between TSEC1_tx of 13-->93 is a constant of 
> 80 decimal.
> > Is this a clue to what the irq should be set to for external IRQ0 in
> > this design?
> 
> 
> Yeah.  112.  However, you really should switch to using 
> arch/powerpc,  
> and device trees.  In that instance, you set the irq to the pin  
> number (1-4), and the kernel will map that based on the 
> interrupt-map  
> property of the pci node.  It was for precisely this type of problem  
> that the irq numbers were virtualized.  The IRQ numbers in arch/ppc  
> actually change depending on whether you've *configured* the 
> CPM or not.
> 
> Andy
> 
> Dear Andy:
> 
> I appreciate your kind advice, it does help converge understanding
> somewhat. I can see how we get the 80 decimal offset with 64 + 32.
> 
> I have commented out the call i8259_init(0,0) in
> arch/ppc/platforms/85xx/mpc85xx_cds_common.c, but retained the call to
> cpm2_init_IRQ(); shortly after that. We are constrained to finish the
> current project with the kernel we started with, so changing 
> from ppc to
> powerpc is really difficult right now.
> 
> When the pci_dev->irq member is set to 112, there is a difference in
> behavior. Now open_pic.c:720 is complaining that 112 is "invalid irq
> 112", so some additional understanding is needed on my part.
> 
> If you get a chance to help me continue to understand how the 8541
> interrupts are sutured into Linux, it would be greatly appreciated.
> 
> Charles Krinke
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