ACPI SCI flags

[Nate Lawson]

On Fri, 9 Apr 2004, Brown, Len wrote:
> Nate,
>
> I think we finally got the vague part of the ACPI spec
> regarding SCI polarity/trigger cleared up.  In Linux
> as of 2.4.26 and 2.6.5 we now do this:
>
> PIC mode:
> 	force level/low via ELCR always.
>
> APIC mode:
> 	no override:
> 		force level/low always
> 	override w/ explicit polarity/trigger:
> 		do exactly what override says
> 	override w/ "compatible" polarity/trigger:
> 		compatible trigger = level
> 		compatible polarity = low
>
> Of course this makes the SCI a special case WRT
> interpreting "compatibility" as compared to other
> overrides.

Thanks for the concise summary.  For an explicit override that is
level/high, this appears not to work in some cases.  Or it may be the
conforming override for irq 2 that is causing the problems.  See this
message:

http://docs.freebsd.org/cgi/getmsg.cgi?fetch=11443+0+current/freebsd-acpi

-Nate