Messages in this thread | | | Date | Thu, 16 Nov 2006 08:05:11 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH] ALSA: hda-intel - Disable MSI support by default |
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On Wed, 15 Nov 2006, linux@horizon.com wrote: > > Er... why can't you test it?
Because if it is level-triggered kind of thing and comes in on the wrong IRQ, and that IRQ is already used by something else, you're basically dead.
IRQ probing is essentially unworkable. We support it for ISA cards (and "ISA" here tends to mean PCMCIA - there are almost no other ISA forms left), but it just doesn't work very well.
> Well, before giving up entirely, assume that *some* device owns that > interrupt, it's just mis-routed. > > So start calling the IRQ handlers for *every* PCI device until the > damn interrupt goes away, or you've really proved that it can't > be shut up.
Sure, you can add crap upon crap upon crap for these things. I pretty much guarantee you that it's not going to work, though. Why? Because developers won't even be working on those machines that have irq routing problems, so they won't be testing things that way, and because if you have irq routing problems, your problems are so fundamental that it really isn't worth it any more.
We've added basic _debugging_ facilities (the whole "nobody cared" thing is really a debugging thing, not a "make it work" thing). That was big, because it used to be that a screaming interrupt just locked up the whole machine - notably you inserted a PCMCIA card, and the machine would just lock up (sometimes it would come back when you removed the card again).
Trying to work around it is basically not worthwhile. You need to fix the problem. Interrupts are very fundamental, you don't want to be guessing about them. If they are wrong, you're screwed.
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