On Tue, 19 Mar 2013, Daniel Vetter wrote:
That might be misleading. It's possible that the erroneous IRQs _are_ being issued but you're simply not aware of them. If the kernel thinks that no device is using IRQ 16 then it will leave that IRQ disabled.
I guess I should have phrased it more precisely, but that's exactly what I expect is happening on my machine: I don't have anything on irq16 (i.e. in non-msi mode the gfx interrupt isn't shared) and hence the irq is completely disabled. Which obviously makes it impossible for me to reproduce the issue. To test that theory, is there a quick way to force-enable a given interrupt, short of just hacking up a 2nd dummy irq handler in my driver?
I don't know of any way. In fact, I have been thinking of writing a test driver module, with a module parameter telling it which IRQ number to register for. It seems like the sort of thing that would be useful to have, from time to time.
Alan Stern