Re: [linuxdc-dev]AICA interrupts

[Adrian M. <ad...@mc...>]

On Tuesday 01 Jan 2002 7:18 pm, M. R. Brown wrote:
> * M. R. Brown <mr...@0x...> on Tue, Jan 01, 2002:
> > * Adrian McMenamin <ad...@mc...> on Tue, Jan 01, 2002:
> > > I am experimenting with the AICA interrupt - HW_EVENT_AICA_SYS - but I
> > > am getting odd results:
> >
> > [...]
> >
> > > When this runs every call to writel(0x20, 0xa07028b8) appears to
> > > generate "unexpected IRQ trap at vector 0b" (though system output
> > > otherwise is normal).
> > >
> > > What have I done wrong?
> >
> > I don't understand why you're getting the "unexpected IRQ ..." message,
> > the DC interrupt-handling code switches off of SH4 IRQ's 9, 11, and 13,
> > so they should always be "expected" and return the virtual IRQ.  See
> > arch/sh/kernel/setup_dc.c::systemasic_irq_demux() for more info.
>
> I added the code you sent in your message.
>
> Hmm, ok, I hit it too, but it's still a bit perplexing since
> /proc/interrupts says AICA interrupts are being triggered;
>
> # cat /proc/interrupts
>            CPU0
>  16:      11594         IPR-IRQ  timer
>  40:          0         IPR-IRQ  sci
>  41:        106         IPR-IRQ  sci
>  42:          0         IPR-IRQ  sci
>  43:        463         IPR-IRQ  sci
>  53:       6933     System ASIC  pvr2 VBL handler
>  81:         32     System ASIC  AICA
>  83:       2597     System ASIC  eth0
>
> But I still get the "unexpected IRQ" messages on playback.
>
> I'm going to dig around the irq and DC irq stuff a bit more, I'll let you
> know when I find out what's going on.
>
> I'm also starting to suspect something a bit more insidious, after catting
> /proc/interrupts a couple of times now I get "Unable to handle kernel
> paging request" register dumps, followed by cat segfaulting.  Something
> looks to be seriously broken.
>
> M. R.


My /proc/interrupts also indicates that AICA interrupts are being handled 
too. I have not had any problems with paging errors.

Further poking about suggests that this does not happen with every write of 
the 0xa07028b8, but only when something is written to the AICA memory. At 
least the number of "Unexpected IRQ traps..." matches the number of writes.

[Interestingly when I removed the enable and disable writes and just kept the 
pending one the whole system froze and could only be restored by switching 
off - not sure why that should be.]