Re: i915_driver_irq_handler: irq 42: nobody cared

From: Chris Wilson
Date: Fri Mar 30 2012 - 08:25:01 EST

On Fri, 30 Mar 2012 14:11:47 +0200, Jiri Slaby <jslaby@xxxxxxx> wrote:
> On 03/30/2012 12:45 PM, Chris Wilson wrote:
> > On Fri, 30 Mar 2012 11:59:28 +0200, Jiri Slaby <jslaby@xxxxxxx> 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.
> This does not make sense, the handler does something different. Even if
> IIR is 0, it still takes a look at pipe stats.

That was introduced in 05eff845a28499762075d3a72e238a31f4d2407c to close
a race where the pipestat triggered an interrupt after we processed the
secondary registers and before reseting the primary.

But the basic premise that we should only enter the interrupt handler
with IIR!=0 holds (presuming non-shared interrupt lines such as MSI).

Chris Wilson, Intel Open Source Technology Centre
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at