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

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Date:	Tue, 10 Apr 2012 09:26:19 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Jiri Slaby <jslaby@...e.cz>
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 Tue, 10 Apr 2012 10:47:49 +0200
Jiri Slaby <jslaby@...e.cz> wrote:

> 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.

Oh sorry missed the PIPE*STAT, I thought it was IMR or something, I
should have read more closely.

So port hotplug is always reporting that port C has a hotplug interrupt
though...  If you write 0x3 back to it does the interrupt stop?

-- 
Jesse Barnes, Intel Open Source Technology Center

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