How to control IRQ polarities on PCI devices?

How to control IRQ polarities on PCI devices?

[Andrew de Quincey]

Hi, I've just tested what Windows XP programs my IO-APIC to with my wavelan 
card (using Softice to interrogate the IO-APIC by hand :)

It turns out that with my latest patch, I am programming the IO-APIC the same 
way it is set up under windows.

Thing is, the IO-APIC is set up to active high, level trigger. This is how it 
is setup under windows as well (the device works under windows).

I'm assuming the device is by default expecting PCI standard IRQs which are 
active LOW, level polarity... which is why I either get no IRQs, or lots of 
rubbish ones.

Is there a standard way of controlling the polarity of IRQs generated by PCI 
devices? This looks like the last issue to be resolved under linux.



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Re: How to control IRQ polarities on PCI devices?

[Andrew de Quincey]

> I'm assuming the device is by default expecting PCI standard IRQs which are
> active LOW, level polarity... which is why I either get no IRQs, or lots of
> rubbish ones.
>
> Is there a standard way of controlling the polarity of IRQs generated by
> PCI devices? This looks like the last issue to be resolved under linux.

Just had the idea to test a different PCI device in this slot. it works fine, 
so it looks like this is just a problem with the wavelan card.

So, unless someone else finds a problem, my latest patch is probably the final 
one for this problem.



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Re: How to control IRQ polarities on PCI devices?

[Andrew de Quincey]

On Saturday 26 July 2003 16:04, Andrew de Quincey wrote:
> > I'm assuming the device is by default expecting PCI standard IRQs which
> > are active LOW, level polarity... which is why I either get no IRQs, or
> > lots of rubbish ones.
> >
> > Is there a standard way of controlling the polarity of IRQs generated by
> > PCI devices? This looks like the last issue to be resolved under linux.
>
> Just had the idea to test a different PCI device in this slot. it works
> fine, so it looks like this is just a problem with the wavelan card.
>
> So, unless someone else finds a problem, my latest patch is probably the
> final one for this problem.

Please ignore this, I was talking absolute rubbish once again. The rtl 
ethernet device is detected fine, but IRQs do not work for it. 

I've posted a message to lkml about this issue. I think this must be something 
in the MCP-T southbridge chip not being set correctly. I have had reports 
that the same thing happens with nforce2 boards from other manufacturers as 
well.



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