linux-kernel - Re: i915_driver_irq_handler: irq 42: nobody cared

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Date:	Tue, 10 Apr 2012 10:47:49 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
CC:	Chris Wilson <chris@...is-wilson.co.uk>,
	Jiri Slaby <jirislaby@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	dri-devel@...ts.freedesktop.org
Subject: Re: i915_driver_irq_handler: irq 42: nobody cared

On 04/09/2012 07:11 PM, Jesse Barnes wrote:
> On Fri, 30 Mar 2012 11:45:43 +0100 Chris Wilson
> <chris@...is-wilson.co.uk> wrote:
> 
>> On Fri, 30 Mar 2012 11:59:28 +0200, Jiri Slaby <jslaby@...e.cz>
>> wrote:
>>> I don't know what to dump more, because iir is obviously zero
>>> too. What other sources of interrupts are on the (G33) chip?
>> 
>> IIR is the master interrupt, with chained secondary interrupt
>> statuses. If IIR is 0, the interrupt wasn't raised by the GPU.
> 
> I've actually seen cases where one of the PIPE*STAT regs is stuck,
> and even if IIR is 0 we still get interrupts... Jiri can you verify
> the PIPE*STAT regs have bits set, maybe one or more we don't check
> for?

Note that I already attached their contents... This is what is in them
(pipes 0 and 1):
[ 3572.968581] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3572.977472] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3576.224839] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3576.243558] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3576.384912] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3576.403462] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3577.464100] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3577.477383] i915_driver_irq_handler: 0=00000000 1=00000000
[ 3577.829016] i915_driver_irq_handler: 0=00020000 1=00000000
[ 3577.830093] i915_driver_irq_handler: 0=00020000 1=00000000

I.e. the handler is called when IIR=0 and both pipe stats are 0.

The stats are dumped this way:
@@ -1416,6 +1417,14 @@ static irqreturn_t
i915_driver_irq_handler(DRM_IRQ_ARGS)
                iir = new_iir;
        }

+       if (ret == IRQ_NONE && printk_ratelimit()) {
+               printk(KERN_DEBUG "%s:", __func__);
+               for_each_pipe(pipe) {
+                       printk(KERN_CONT " %d=%.8x", pipe,
+                                       pipe_stats[pipe]);
+               }
+       }
+
        return ret;
 }

thanks,
-- 
js
suse labs

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