On Mon, Mar 18, 2013 at 2:12 AM, Jiri Kosina jkosina@suse.cz wrote:
On Fri, 15 Mar 2013, Yinghai Lu 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?
Yes, switching from MSI to IO-APIC-fasteoi makes the report about lost interrupts go away.
My understanding from the other mail is that DAniel Vetter already has an idea what might be going wrong with IRQ acking on GM45 chipsets; hopefully this datapoint regarding MSI will fit into it.
What is /proc/interrupts difference between with and without pci=nomsi ?
drm is forced to share irq 16?
Thanks
Yinghai