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Message-ID: <CAMuHMdUZ-fTKPk1kXodjg1yi5vm3RZJ=wO9o5afA81yNvt0KYA@mail.gmail.com>
Date: Tue, 3 May 2022 09:02:11 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Rob Landley <rob@...dley.net>
Cc: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
Sergey Shtylyov <s.shtylyov@....ru>,
Rich Felker <dalias@...c.org>,
Linux-sh list <linux-sh@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
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@...dley.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@...ux-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
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