Re: [3.9-rc1] irq 16: nobody cared (was [3.9-rc1] very poorinterrupt responses)

From: Thomas Meyer
Date: Mon Mar 18 2013 - 03:15:38 EST

My laptop is an Acer 1810T. I see this error message each boot.

Kind regards

Jiri Kosina <jkosina@xxxxxxx> schrieb:

>On Fri, 15 Mar 2013, Jiri Kosina wrote:
>> > I have the same problem on my Lenovo T500. I think the graphics card is
>> > involved.
>> >
>> > This laptop has "hybrid graphics" - one Intel GMA 4500MHD and one ATI
>> > Mobility Radeon HD 3650. When I boot with the Intel card, I get "irq 16:
>> > nobody cared" during boot, not when I boot with the ATI card.
>> Confirming this. After a lot of hassle, I have bisected this reliably to
>> commit 28c70f162a315bdcfbe0bf940a740ef8bfb918d6
>> Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
>> Date: Sat Dec 1 13:53:45 2012 +0100
>> drm/i915: use the gmbus irq for waits
>> Adding Daniel, Imre and Daniel to CC while I will try to figure out what's
>> happening in parallel.
>> Attaching dmesg.txt from the machine with 28c70f162a as head, with
>> drm.debug=0xe.
>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.
>Jiri Kosina
>SUSE Labs
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