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List:       acpi4linux
Subject:    Re: [ACPI] ACPI ignoring IRQ flags in PRT
From:       Andrew de Quincey <adq_dvb () lidskialf ! net>
Date:       2003-07-13 19:49:13
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On Sunday 13 July 2003 15:23, Matthew Wilcox wrote:
> On Sun, Jul 13, 2003 at 02:52:38PM +0100, Andrew de Quincey wrote:
> > Hi, from my understanding of the ACPI spec, each IRQ as specified in the
> > _PRT has additional flags associated with it (e.g. specifying the
> > polarity, level etc) that should be used for this IRQ.
> >
> > The Linux ACPI code seems to be ignoring these, and hardcodes them to the
> > values that cause problems for me. Is there a reason, or has that code
> > just not been written yet?
>
> you can't mean the _PRT.  the _PRT describes PCI interrupts, and those
> have their polarity and trigger specified by the PCI spec.  i suspect you
> mean someting else, but i'm not sure what.  can't be the SCI interrupt
> since that's defined to be level, low, sharable.
>
> some of the ia64 acpi code pays attention to polarity and edge vs level.
> now that we know this is an issue on x86, maybe some more people will be
> interested in thinking about how to fix this properly.  here's what we
> currently have on ia64:
>
> int acpi_register_irq (u32 gsi, u32 polarity, u32 trigger);

My first thoughts are:

Need to modify io_apic.c/io_apic_set_pci_routing() in the i386 architecture so 
it takes the polarity and trigger.

In i386, the actual PRT parsing and calls to io_apic_set_pci_routing() is done 
by mpparse.c/mp_parse_prt(), so that has to change... possibly not the API 
though.

I'm going to have a look into developing a prototype patch for this this 
evening.

As for Jurriaan's problem, I think it _may_ be a slightly different issue... 
so it is probably best to sort this on a board I have access to, then see if 
it needs more development iterations....



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