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Date: Wed, 30 Jul 2008 00:24:48 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-core] Error propagating ISR to Linux domain
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To: Ulrich Schwab <uli.schwab@domain.hid>
Cc: xenomai-core <xenomai@xenomai.org>

Ulrich Schwab wrote:
> On Tue, Jul 29, 2008 at 4:20 PM, Gilles Chanteperdrix
> <gilles.chanteperdrix@xenomai.org> wrote:
>> Gilles Chanteperdrix wrote:
>>> Ulrich Schwab wrote:
>>>> why not checking for irq origin like this:
>>>> int my_isr_handler (xnintr_t *irq)
>>>> {
>>>>  if ( ! test_my_card_for_irq_origin )
>>>>     return XN_ISR_NONE | XN_ISR_PROPAGATE;
>>>>   ... /* handling */
>>>>  return XN_ISR_HANDLED;
>>>> }
>>>>
>>>> this way XN_ISR_PROPAGATE is never returned in the not-shared case.
>>> I think this idea needs an answer; the answer is no: it will not work.
>>> Because the IRQ will remain masked until Linux handles it, which
>>> basically means that the RT irq will wait for non-RT activity, you loose
>>> real-time response.
>> It will not work, but not for the reason I mention: Adeos WILL re-enable
>> the IRQ at interrupt controller level after the end of this handler,
>> however, since the interrupt was not cleared on the peripheral side, the
>> peripheral will reassert the interrupt when the interrupt is unmasked at
>> interrupt controller level, so the CPU will enter an infinite loop
>> invoking the ISR.
>>
>> --
>>                                                 Gilles.
>>
> Are You sure?
> IIRC the infinte loop You describe occurs when XN_ISR_PROPAGATE is
> removed from the code above.

Yes, I am sure, the only solution that works is the one I posted.

-- 


					    Gilles.