gm45 intel gfx can generate non-MSI irq# in MSI mode (was Re: [PATCH] drm/i915: stop using GMBUS IRQs on Gen4 chips (was Re: [3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poor interrupt responses

[Yinghai Lu]

On Tue, Mar 19, 2013 at 9:54 AM, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:

> 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?

You may try to add another request_irq()
after i915_load_modeset_init==>drm_irq_install.
That could install one dummy action for ioapic irq for i915.

Also you may need to add one quirk that does not disable intx during
msi enabling like:
DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,
                        0x2e22,
                        quirk_msi_intx_disable_bug);

Thanks

Yinghai