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Re: sa11x0 spurious interrupts


Gary Thomas wrote:
> 
> On 13-Feb-2001 Jonathan Larmour wrote:
> > Robin Farine wrote:
> >>
> >> Hello,
> >>
> >> While looking at the way the sa11x0 hal's routine 'hal_IRQ_handler()' decodes
> >> interrupt sources, I noticed that when it does not find an interrupt source,
> >> the routine returns CYGNUM_HAL_INTERRUPT_NONE, which equals to -1 for this
> >> platform. However, the common ARM code in "vectors.S" assumes that a spurious
> >> interrupt always have the vector #0. And worse, 'handle_IRQ_or_FIQ' will call
> >> 'hal_interrupt_handlers[-1]' which contains 0 and thus reboot!
> >>
> >> Did I miss something?
> >
> > I don't think so. 0 can be a valid ISR. What's worse is that the default
> > ISR in hal/common also returns 0 to indicate a spurious interrupt.
> 
> The default ISR handler returning 0 is a whole separate matter.

Oops, I read too much into the name hal_IRQ_handler.
 
> > Anyone got any opinions why this isn't simply all wrong?
> 
> Actually, it does seem to be rather messed up.  It comes from having a large
> number of ports and this particular behaviour is platform specific, thus
> we've somehow ended up with no less than 3 different answers here.

Yes I noticed on the AEB that it returns 13!
 
> These should all be changed to return CYGNUM_HAL_INTERRUPT_NONE

where CYGNUM_HAL_INTERRUPT_NONE is defined on every platform to be -1 I
presume.

> and have
> the code in 'vectors.S' handle this as a special case.  However, what one
> actually does when there is a spurious interrupt is tinder for a large
> flame war :-)

It depends on how spurious is spurious :).

Robin would you care to have a go at fixing this for all the
hal_IRQ_handlers, i.e. in the aeb, pid, cma230, ebsa285, edb7xxx, and
sa11x0/var dirs? As well as vector.S of course. ChangeLog entries would be
superb :-).

Jifl
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