PCI interrupt question

Benjamin Herrenschmidt benh at kernel.crashing.org
Fri Dec 4 20:02:32 EST 2009

>  So are you saying linux should be writing the irq number to the
> INTERRUPT_LINE config reg?  This is what I expected but I do not see
> it.  

No it won't necessarily touch it, this is not terribly useful anyways.
Linux will assign an interrupt based on the informations from the
device-tree and you should be able to retrieve it in pci_dev->irq.

>  I believe the DTS is being parsed properly and the connection is made
> to the correct interrupt line on the device.  But somebody still needs
> to assign and IRQ number, right?  

What do you mean ? If the connection is made properly, the code will
obtain an HW IRQ input number on the UIC and will map it to a linux
virtual IRQ number which you can find in pci_dev->irq.
> This is the part that is not clear,
> there is an irq field in pci_dev structure which is filled in after
> looking at the DTS and I just want to be sure this is the irq number to
> be used when calling request_irq.

Yes, it is.

If things don't work, it's possible that you assigned the wrong number
in the device-tree ?


> thanks,
> jeff
> > These comments might not be 100% correct, but the list of things
> > to check should be close enough for you to track down your
> > problem.
> > 
> > Cheers,
> > Dave
> > 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev at lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

More information about the Linuxppc-dev mailing list