Changing PCI board's IRQ

Changing PCI board's IRQ

[Raphael Derosso Pereira - DephiNit]

Hello,

One computer that I administer have a IRQ conflict between a sound card and a 
ethernet card. Both share the IRQ 11.
I don't have physical access to the computer, so I tried to change the IRQ 
using the 'setpci' command.

# setpci -v -s 0:7.5 INTERRUPT_LINE=08
00:07.5:3c 08
#

But, after that, when I did a 

# lspci -vv -s 0:7.5
00:07.5 Multimedia audio controller: VIA Technologies, Inc. AC97 Audio 
Controller (rev 50)
        Subsystem: Biostar Microtech Int'l Corp: Unknown device 0032
        Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- 
Stepping- SERR- FastB2B-
        Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- 
<TAbort- <MAbort- >SERR- <PERR-
        Interrupt: pin C routed to IRQ 11
        Region 0: I/O ports at dc00 [size=256]
        Region 1: I/O ports at e000 [size=4]
        Region 2: I/O ports at e400 [size=4]
        Capabilities: [c0] Power Management version 2
                Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA 
PME(D0-,D1-,D2-,D3hot-,D3cold-)
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-


After some experience (like rebooting... arg!) i tried:

# lspci -vv -H1 -s 0:7.5
<cut>
        Interrupt: pin C routed to IRQ 8
        Region 0: I/O ports at dc00
<cut>

So, it seems that either I cannot change the Interrupt line number throught 
software (and the -H1 is tricky) or the /proc/pci (and /proc/bus/pci) is not 
getting updated.

Is that a problem or am I missing the point?

P.S.: Please Reply direct to me (or send me a copy) because I can not 
"afford" the traffic of linux-kernel. :)

-- 
 Raphael Derosso Pereira - DephiNit

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Re: Changing PCI board's IRQ

[Harald Welte]

On Sat, Feb 16, 2002 at 09:25:27PM -0200, Raphael Derosso Pereira - DephiNit wrote:
> Hello,
> 
> One computer that I administer have a IRQ conflict between a sound card and a 
> ethernet card. Both share the IRQ 11.
> I don't have physical access to the computer, so I tried to change the IRQ 
> using the 'setpci' command.
> 
> # setpci -v -s 0:7.5 INTERRUPT_LINE=08
> 00:07.5:3c 08
> #


well, this is obviously the wrong solution.  If both boards are PCI boards,
they can easily share the IRQ between them. 

If one of the boards is an ISA device, configure your BIOS correctly 
(i.e. telling it that IRQ11 is used by a non-pnp legacy ISA device).

> So, it seems that either I cannot change the Interrupt line number throught 
> software (and the -H1 is tricky) or the /proc/pci (and /proc/bus/pci) is not 
> getting updated.

You can't just change the IRQ in pci config space.  You will not change the
real IRQ mapping but just somthing the BIOS wrote there during initialization.

> Is that a problem or am I missing the point?
> 
-- 
Live long and prosper
- Harald Welte / laforge@gnumonks.org               http://www.gnumonks.org/
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