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

[Chris Wilson]

On Mon, 2009-04-20 at 18:59 -0700, Eric Anholt wrote:
> On Mon, 2009-04-20 at 18:53 -0700, Jesse Barnes wrote:
> > On Mon, 20 Apr 2009 18:37:54 -0700
> > Eric Anholt <eric at anholt.net> wrote:
> > > 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...
> 
> It was complete system lockup reports from people testing the branch I'd
> done for error reporting.

Been there, done that, posted workaround. ;-)

This was the essential part to clear the persistent interrupt on my
i915:
	I915_WRITE(EIR, eir);
	eir = I915_READ16(EIR);
	if (eir != 0) {
		DRM_INFO("Potential un-cleared error bits: 0x%04x, "
			 "disabling.\n",
			 eir);

		I915_WRITE16(EMR, I915_READ(EMR) | eir);

		/* Clear the Master Error bit as well, since the EIR != 0 */
		I915_WRITE(IIR, I915_RENDER_COMMAND_PARSER_ERROR_INTERRUPT);
	}
-ickle