Re: [ACPI] [PATCH] add acpi_interrupt_to_irq

From: Bjorn Helgaas <bjorn.helgaas_at_hp.com>
Date: 2004-01-24 03:35:50
On Thursday 22 January 2004 8:36 pm, Nakajima, Jun wrote:
> > What does "vector" mean?  
> For MSI, vector means the (external) interrupt vector, i.e. the index in
> the IDT for MSI on x86. So acpi_irq_to_vector() is correct in that case.
> ACPI looks at IRQ or GSI (Global system interrupt) vector (yes, it's
> confusing). SOMETHING should be irq or gsi, as David suggested.
> 
> Since MSI does not require IRQ (but external interrupt vector), the way
> we did for x86 was to use the vector to unify IRQ and vector. So
> request_irq() actually gets the interrupt vector number, instead of irq.
> That's the reason I preferred acpi_irq_to_vector() in that code with MSI
> configured.

Sorry to drag this out even longer...  I promise I'll shut up
after this :-)

But this business about request_irq() getting an MSI interrupt vector
number, not an irq, is just a detail of the MSI and architecture
implementation.  Surely ACPI should just use the abstract Linux
interrupt interface (request_irq(), free_irq(), etc), which uses
the "irq" terminology, and should remain ignorant of whether MSI
is even present.

Bjorn

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Received on Fri Jan 23 11:36:40 2004

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