linux-kernel - Re: PCI Interrupt

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Message-Id: <200709181642.23070.rjw@sisk.pl>
Date:	Tue, 18 Sep 2007 16:42:22 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"linux-os \(Dick Johnson\)" <linux-os@...logic.com>
Cc:	Duncan.Perrett@...kta.com,
	"Linux kernel" <linux-kernel@...r.kernel.org>
Subject: Re: PCI Interrupt

On Tuesday, 18 September 2007 15:57, linux-os (Dick Johnson) wrote:
> 
> On Tue, 18 Sep 2007 Duncan.Perrett@...kta.com wrote:
> 
> >
> > I have a CAN PCI card installed on my Ubuntu box.
> > I understand that PCI interrupts should be level rather than edge
> > triggered.
> >
> > The output of cat /proc/interrupts is :-
> >
> >           CPU0
> >  0:    1614601    IO-APIC-edge  timer
> >  1:        164    IO-APIC-edge  i8042
> >  8:          3    IO-APIC-edge  rtc
> >  9:          1   IO-APIC-level  acpi
> > 12:          0    IO-APIC-edge  CAN-ACx-PCI_01
> > 14:      65786    IO-APIC-edge  ide0
> > 169:       3220   IO-APIC-level  eth0, i915@pci:0000:00:02.0
> > 177:      46459   IO-APIC-level  eth1
> > 209:          0   IO-APIC-level  uhci_hcd:usb3, eth2
> > 217:          2   IO-APIC-level  uhci_hcd:usb1, ehci_hcd:usb4
> > 225:        697   IO-APIC-level  uhci_hcd:usb2
> > NMI:          0
> > LOC:    1614399
> > ERR:          0
> > MIS:          0
> >
> > You see that irq 12 CAN-ACx-PCI_01 is edge triggered.
> > Is there any way of forcing the BIOS to see the interrupt as a
> > level-triggered one?
> 
> It's done in the driver. IRQ12 can be shared, so the driver
> needs to request the IRQ as a shared interrupt.

Hm, edge-triggered interrupts cannot be shared, AFAIK.

Greetings,
Rafael
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