[3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt responses)

[Yinghai Lu]

On Fri, Mar 15, 2013 at 8:14 AM, Jiri Kosina <jkosina at suse.cz> wrote:

> Just a datapoint -- I have put a trivial debugging patch in place, and it
> reveals that "nobody cared" for irq 16 happens long after last
>
>         I915_WRITE(GMBUS4 + reg_offset, 0);
>
> has been performed in gmbus_wait_hw_status(). On the other hand, if I
> comment out both GMBUS4 register offset writes in gmbus_wait_hw_status(),
> then it of course falls back to GPIO bit-banging, but the "nobody cared"
> for irq 16 is gone.
>
> So it seems like something gets severely confused by the I915_WRITE to
> GMBUS4 + reg_offset. So far this seems to have been reported solely on
> Lenovos as far as I can see (although a completely different types), so it
> might be some platform-specific quirk?
>
> Honestly, I still don't understand how all the GMBUS stuff relates to IRQ
> 16 at all.

that device is using
i915 0000:00:02.0: irq 44 for MSI/MSI-X

so can you try to boot with pci=nomsi?