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Re: IRQ problem on cobalt / 2.6.6

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: IRQ problem on cobalt / 2.6.6
From: Johannes Stezenbach <js@convergence.de>
Date: Sun, 16 May 2004 19:21:43 +0200
Cc: Kieran Fulke <kieran@pawsoff.org>, linux-mips@linux-mips.org
In-reply-to: <20040516170445.GA4793@linux-mips.org>
Mail-followup-to: Johannes Stezenbach <js@convergence.de>, Ralf Baechle <ralf@linux-mips.org>, Kieran Fulke <kieran@pawsoff.org>, linux-mips@linux-mips.org
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References: <20040513183059.GA25743@getyour.pawsoff.org> <40A478B0.3070005@bitbox.co.uk> <20040516113622.GA14049@getyour.pawsoff.org> <20040516152113.GA9390@convergence.de> <20040516170445.GA4793@linux-mips.org>
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On Sun, May 16, 2004 at 07:04:45PM +0200, Ralf Baechle wrote:
> On Sun, May 16, 2004 at 05:21:13PM +0200, Johannes Stezenbach wrote:
> 
> > In essence, I believe something other than the saa7146 must be asserting
> > irq 23.  Or is it possible that a bug in the PCI init stuff in
> > saa7146_core.c can
> > cause this? Any hints how we could debug this would be welcome.
> 
> arch/mips/cobalt/irq.c:cobalt_irq() looks pretty suspect.  It connects
> CAUSEF_IP7 and interrupt 23 - but the CPU's builtin count / compare
> interrupt already uses this bit.
> 
> Sharing the timer interrupt with something else isn't impossible but seems
> a less than bright thing to do.  Somebody with production hw to test
> should compare this interrupt dispatch function with old working code
> from 2.2 or 2.4 ...

Sorry if I snipped too much from Kieran's mail. He reported
a tulip network card works in the same PCI slot, and it uses
irq 23, too.

But this one from Kieran's mail looks dubious:

> > cat /proc/interrupts
> >            CPU0
> >   2:          0          XT-PIC  cascade
> >  14:      27636          XT-PIC  ide0
> >  18:     435142            MIPS  timer
> >  19:        696            MIPS  eth0
> >  20:          7            MIPS  eth2
> >  21:        302            MIPS  serial
> >  22:          0            MIPS  cascade
> >  23:     100002            MIPS  eth1

100002 is just where note_interrupt() disables an unhandled irq, so
maybe Kieran's report that the tulip card works was wrong?


Johannes

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