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    SubjectRe: better leve triggered IRQ management needed


    On Sat, 29 Apr 2006, Alan Cox wrote:
    >
    > Trying to guess the current IRQ level v edge on a PC is very hard.
    > Trying to set it correctly from the driver is rather easier.

    I disagree. It's not any easier at all.

    On PC's (x86 and x86-64) we actually already set the ELCR as well as we
    can (look for "eisa_set_level_irq()"). And a driver _literally_ cannot
    change it from the system value, because of the polarity confusion.

    In the other cases (IO-APIC) we usually have it level, but when we have it
    marked as an edge, there is almost always a real reason for that too (ie
    legacy interrupt, it really _is_ edge-high, not level-low).

    Linus
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