i915_driver_irq_handler: irq 42: nobody cared [generic IRQ handling broken?]

Daniel Vetter daniel at ffwll.ch
Tue Apr 10 01:50:14 PDT 2012

On Fri, Apr 6, 2012 at 23:31, Jiri Slaby <jslaby at suse.cz> wrote:
>> That was introduced in 05eff845a28499762075d3a72e238a31f4d2407c to close
>> a race where the pipestat triggered an interrupt after we processed the
>> secondary registers and before reseting the primary.
>> But the basic premise that we should only enter the interrupt handler
>> with IIR!=0 holds (presuming non-shared interrupt lines such as MSI).
> Ok, this behavior is definitely new. I get several "nobody cared" about
> this interrupt a week. This never used to happen. And something weird
> emerges in /proc/interrupts when this happens:
>  42:    1003292    1212890   PCI-MSI-edge      �s����:0000:00:02.0
> instead of
>  42:    1006715    1218472   PCI-MSI-edge      i915 at pci:0000:00:02.0

This looks ugly. Can you try to reproduce on 3.4-rc2? That should
contain everything that -next currently contains drm/i915-wise. If it
still happens there, please bisect it.

Also please check whether any of the subordinate interrupt regs
(pipestat) is stuck and might cause these interrupts as Jesse

Thanks, Daniel
Daniel Vetter
daniel.vetter at ffwll.ch - +41 (0) 79 364 57 48 - http://blog.ffwll.ch

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