From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gary Thomas To: Jonathan Larmour Cc: ecos-discuss@sources.redhat.com, Robin Farine Subject: Re: [ECOS] sa11x0 spurious interrupts Date: Tue, 13 Feb 2001 09:56:00 -0000 Message-id: References: <3A896C61.FD04D794@redhat.com> X-SW-Source: 2001-02/msg00205.html 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. > > 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. These should all be changed to return CYGNUM_HAL_INTERRUPT_NONE 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 :-)