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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Mon, 10 Jul 2023 09:03:19 +0200
Message-ID: <CAMuHMdW=WDuqgXk_51T341vgXrcxYPO34ou=rKHZrZj8Yiw6Rw@mail.gmail.com>
Subject: Re: [PATCH] [RFT] sh: mach-r2d: Handle virq offset in cascaded IRL demux
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Sergey Shtylyov <s.shtylyov@omp.ru>,
        John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, linux-sh@vger.kernel.org,
        linux-kernel@vger.kernel.org
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Hi Günter,

On Mon, Jul 10, 2023 at 3:13 AM Guenter Roeck <linux@roeck-us.net> wrote:
> On 7/9/23 04:15, Geert Uytterhoeven wrote:
> > When booting rts7751r2dplus_defconfig on QEMU, the system hangs due to
> > an interrupt storm on IRQ 20.  IRQ 20 aka event 0x280 is a cascaded IRL
> > interrupt, which maps to IRQ_VOYAGER, the interrupt used by the Silicon
> > Motion SM501 multimedia companion chip.  As rts7751r2d_irq_demux() does
> > not take into account the new virq offset, the interrupt is no longer
> > translated, leading to an unhandled interrupt.
> >
> > Fix this by taking into account the virq offset when translating
> > cascaded IRL interrupts.
> >
> > Fixes: a8ac2961148e8c72 ("sh: Avoid using IRQ0 on SH3 and SH4")
> > Reported-by: Guenter Roeck <linux@roeck-us.net>
> > Closes: https://lore.kernel.org/r/fbfea3ad-d327-4ad5-ac9c-648c7ca3fe1f@roeck-us.net
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > ---
> > Highlander and Dreamcast probably have the same issue.
> > I'll send patches for these later...
>
> dreamcast doesn't build in linux-next, just in case you didn't notice.

Indeed, I hadn't tested that.
My current tree isn't based on linux-next, but did have a build
failure in the cdrom code, for which I had found your fix (thanks!) in
linux-next...

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