Messages in this thread | | | Date | Wed, 1 Aug 2012 16:39:47 +0200 | From | Thierry Reding <> | Subject | Re: x86 and I/O APIC IRQ domains |
| |
On Wed, Aug 01, 2012 at 03:58:39PM +0200, Thierry Reding wrote: > Hi, > > 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.
So it turns out that this is not due to init_ISA_irqs(). However, increasing NR_IRQS_LEGACY to 32 allows the code to get past that.
> 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. > > 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?
This crash is in irq_domain_add_legacy() which tries to call the IRQ domain's .map() function, which isn't implemented for the I/O APIC. Adding an empty function allows the system to boot without any noticeable errors.
I need to read up on the whole I/O APIC stuff because this is not really a fix and I don't know any better. Also, the CE4100 should exhibit the same issue after the above-mentioned commit. Can somebody more knowledgeable shed some light on this?
Thierry [unhandled content-type:application/pgp-signature] | |