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

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Date:	Tue, 10 Apr 2012 11:34:48 -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, daniel@...ll.ch
Subject: Re: i915_driver_irq_handler: irq 42: nobody cared

On Tue, 10 Apr 2012 20:11:29 +0200
Jiri Slaby <jslaby@...e.cz> wrote:

> On 04/10/2012 06:26 PM, Jesse Barnes wrote:
> > 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?
> 
> I'm not sure I got it right. This doesn't help:
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1416,6 +1416,17 @@ static irqreturn_t
> i915_driver_irq_handler(DRM_IRQ_ARGS)
>                 iir = new_iir;
>         }
> 
> +       if (ret == IRQ_NONE) {
> +               u32 hp = I915_READ(PORT_HOTPLUG_STAT);
> +               if (hp) {
> +                       I915_WRITE(PORT_HOTPLUG_STAT, hp);
> +                       I915_READ(PORT_HOTPLUG_STAT);
> +               }
> +
> +               if (printk_ratelimit())
> +                       printk(KERN_DEBUG "%s: %.8x\n", __func__, hp);
> +
> +       }
> 
>         return ret;
>  }

Yeah that looks right, you still get 0x300?

You could try masking hotplug interrupts altogether.

Also, just to sanity check things, can you look at the output of "lspci
-s 02.0 -vvv -xxx" and see if the "INTx" field is + or -?  If it's +,
then the interrupt is definitely coming from an un-acked IRQ source on
the gfx device.  If it's INTx-, it means something in one of the upper
MSI layers isn't getting handled right.

-- 
Jesse Barnes, Intel Open Source Technology Center

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