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    SubjectRe: Interrupt sharing
    Date

    ----- Original Message -----
    From: "Jeff Garzik" <jgarzik@mandrakesoft.mandrakesoft.com>
    To: "Mahadev K Cholachagudda" <mahadev_kc@yahoo.com>
    Cc: <linux-kernel@vger.kernel.org>
    Sent: Monday, September 25, 2000 7:00 PM
    Subject: Re: Interrupt sharing


    >
    >
    > On Mon, 25 Sep 2000, Mahadev K Cholachagudda wrote:
    >
    > > Hello to all,
    > >
    > > I have one doubt and is as below.
    > >
    > >
    > > Suppose say the two drivers driver1 and driver2 will install the ISR for
    a
    > > particular interrupt, say UART0.
    > > After some time the interrupt is generated. At this moment, which
    driver's
    > > ISR is going to execute ?.
    > >
    > > If driver1 ISR is get executed, will the driver2's ISR is going to
    execute
    > > ?. If say driver2's ISR is going to execute, Is the data that interrupt
    > > generated is going to be emulated to the driver2's ISR.
    >
    > When an interrupt is delivered, the kernel calls ALL interrupt handlers
    > registered for that interrupt. That means all drivers capable of
    > sharing interrupts should, ideally, have code in their interrupt handler
    > to exit ASAP if no work is necessary.
    >
    > status = RTL_R16(IntrStatus);
    > /* exit ASAP if no interrupt conditions (0), or
    > * if the hardware was unplugged (0xFFFF)
    > */
    > if ((status == 0) || (status == 0xFFFF))
    > return;
    >

    If this is the case, if i am not wrong the data which is to be delivered to
    the ISR will be emulated to the each drivers ISR. Is it true ?




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