Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 3 May 2022 09:02:11 +0200 | Subject | Re: [PATCH v3] sh: avoid using IRQ0 on SH3/4 |
| |
Hi Rob,
On Mon, May 2, 2022 at 10:02 PM Rob Landley <rob@landley.net> wrote: > Sounds like it's now outside of the IRQ range allocation, but I can't find where > that's requested when registering the controller? (What is a "swizzle" anyway?)
PCI slots have 4 interrupts (#A, #B, #C, #D). In machines with multiple slots, the interrupts lines are "swizzled", to avoid that all cards using a single interrupt are mapped to the same host interrupt.
Typically, the mapping is:
host_irq = bus_irqs[(slot + irq_pin) % 4];
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
| |