[Intel-gfx] [PATCH] i915: add error detection & state dumping

Jesse Barnes jbarnes at virtuousgeek.org
Tue Apr 21 03:53:04 CEST 2009

On Mon, 20 Apr 2009 18:37:54 -0700
Eric Anholt <eric at anholt.net> wrote:

> On Mon, 2009-04-20 at 15:38 -0700, Jesse Barnes wrote:
> > Add error state detection and state dumping to the i915 driver.
> > 
> > This is still pretty rudimentary, since it just dumps error state at
> > detect time or when the i915_error_state file from debugfs is
> > read.  To really figure things out it would be good to track the
> > PGTBL_ER offset back to its originating batchbuffer and process,
> > and save the batchbuffer for later fetch & decode by the dumping
> > tool.
> > 
> > We'd also like to be able to recover from errors by killing the
> > offending process and/or resetting the chip as needed.
> > 
> > I've tested this on 965, but re-reviewed the offets for pre-965
> > (good thing I did, all the debug registers moved), so it should
> > work on earlier chips too.  However I've only successfully dumped
> > instruction parse errors, it would be good to get additional
> > testing for pipe underruns & page table errors.
> Having had problems with the interrupt handler part of error detection
> before, I'm pretty wary until we've triggered a *lot* of errors with
> it. But I'd love to pull a patch that was just the debugfs bits.

What did you run into?  An unceasing flood of error interrupts or
something else?

FWIW it doesn't trigger in normal operation (at least
not apparently on my 965).  I guess we could make it a module option or
add a count if you want, but my eventual intent would be to catch the
first real error and take some action on it.  But that will only work
if the error detection is precise...

Either way, feel free to trim the i915_irq part of it if you want,
since the debugfs part of it is useful by itself.

Jesse Barnes, Intel Open Source Technology Center

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