Messages in this thread | | | Date | Wed, 01 Aug 2012 16:45:41 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: x86 and I/O APIC IRQ domains |
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On 08/01/2012 03:58 PM, Thierry Reding wrote: > I've been working on an x86 platform and want to use DT. However I've > hit a snag when trying to instantiate the I/O APIC. I've been trying to > follow what the CE4100 does and most things seem to work fine but when > I add the DT node for the I/O APIC things start to fail. I've been able > to trace the issue to x86_add_irq_domains(), which in turn calls > ioapic_add_ofnode() from which irq_domain_add_legacy() is called. > > The platform that I use hits the WARN_ON(!irq_data || irq_data->domain). > Looking further this seems to be caused by all irq_get_irq_data(irq) > returning NULL for irq>= 16. That in turn I think is due to > init_ISA_irqs() setting up only the first NR_IRQS_LEGACY interrupts. > However the call to irq_domain_add_legacy() wants 32 interrupts.
The IOAPIC knows how many sources are available and this number should be used instead of 32. This won't solve the problem with get_irq_data() for the second ioapic which might be available in the system.
The reason why there is no irq_data() available is that this is allocated by io_apic_setup_irq_pin_once() which is now called too late. Usually a PCI device does a pci_enable() call and then we do all this. So to keep the function happy you should preallocate all interrupts which are offered. Ah, and you may need a map function which does nothing because the programming is done at io_apic_setup_irq_pin_once() time. Maybe you could live with irq_domain_add_linear() instead. Not sure how important it is to keep rtc at a fixed irq. I think as far as the IOAPIC is concerned, it could be programmed to another number but I kept it in sync. However parts of the ioapic code rely on gsi_number == irq number so maybe we should preallocate the irq_data and use a dummy map() function for the start.
> This was introduced by commit b4e5185 "irq_domain/x86: Convert x86 > (embedded) to use common irq_domain)". I wonder what I'm doing wrong. I > don't get how this is made to work on CE4100. Currently it does not
> Later the code crashes, but I can't exactly pinpoint the location > because the oops doesn't fit on the screen. I don't have a serial port > that I can use instead, so is there anything else I can do to obtain a > complete backtrace?
There is an option which delays each printk by a few msecs. Maybe this could help.
> > Thierry
Sebastian
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