[Intel-gfx] [PATCH] drm/i915/guc: Fix request re-submission after reset

[Chris Wilson]

On Thu, Mar 09, 2017 at 10:19:10AM +0000, Chris Wilson wrote:
> On Thu, Mar 09, 2017 at 10:05:21AM +0000, Tvrtko Ursulin wrote:
> > From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > 
> > In order to ensure no missed interrupts we must first re-direct
> > the interrupts to GuC, and only then re-submit the requests to
> > be replayed after a GPU reset. Otherwise context switch can fire
> > before GuC has been set up to receive it triggering more hangs.
> > 
> > Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > Cc: Oscar Mateo <oscar.mateo at intel.com>
> > Cc: Sagar Arun Kamble <sagar.a.kamble at intel.com>
> > Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_guc_submission.c | 58 +++++++++++++++++++++++++++---
> >  drivers/gpu/drm/i915/intel_guc_loader.c    | 47 ------------------------
> >  2 files changed, 54 insertions(+), 51 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> > index beb38e30d0e9..5b8ec0fab563 100644
> > --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> > +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> > @@ -936,6 +936,52 @@ static void guc_reset_wq(struct i915_guc_client *client)
> >  	client->wq_tail = 0;
> >  }
> >  
> > +static void guc_interrupts_capture(struct drm_i915_private *dev_priv)
> > +{
> > +	struct intel_engine_cs *engine;
> > +	enum intel_engine_id id;
> > +	int irqs;
> > +	u32 tmp;
> > +
> > +	/* tell all command streamers to forward interrupts (but not vblank) to GuC */
> > +	irqs = _MASKED_BIT_ENABLE(GFX_INTERRUPT_STEERING);
> > +	for_each_engine(engine, dev_priv, id)
> > +		I915_WRITE(RING_MODE_GEN7(engine), irqs);
> > +
> > +	/* route USER_INTERRUPT to Host, all others are sent to GuC. */
> > +	irqs = GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
> > +	       GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT;
> > +	/* These three registers have the same bit definitions */
> > +	I915_WRITE(GUC_BCS_RCS_IER, ~irqs);
> > +	I915_WRITE(GUC_VCS2_VCS1_IER, ~irqs);
> > +	I915_WRITE(GUC_WD_VECS_IER, ~irqs);
> > +
> > +	/*
> > +	 * The REDIRECT_TO_GUC bit of the PMINTRMSK register directs all
> > +	 * (unmasked) PM interrupts to the GuC. All other bits of this
> > +	 * register *disable* generation of a specific interrupt.
> > +	 *
> > +	 * 'pm_intr_keep' indicates bits that are NOT to be set when
> > +	 * writing to the PM interrupt mask register, i.e. interrupts
> > +	 * that must not be disabled.
> > +	 *
> > +	 * If the GuC is handling these interrupts, then we must not let
> > +	 * the PM code disable ANY interrupt that the GuC is expecting.
> > +	 * So for each ENABLED (0) bit in this register, we must SET the
> > +	 * bit in pm_intr_keep so that it's left enabled for the GuC.
> > +	 *
> > +	 * OTOH the REDIRECT_TO_GUC bit is initially SET in pm_intr_keep
> > +	 * (so interrupts go to the DISPLAY unit at first); but here we
> > +	 * need to CLEAR that bit, which will result in the register bit
> > +	 * being left SET!
> > +	 */
> > +	tmp = I915_READ(GEN6_PMINTRMSK);
> > +	if (tmp & GEN8_PMINTR_REDIRECT_TO_GUC) {
> > +		dev_priv->rps.pm_intr_keep |= ~tmp;
> > +		dev_priv->rps.pm_intr_keep &= ~GEN8_PMINTR_REDIRECT_TO_GUC;
> > +	}
> 
> Let me just remove this code first (drm/i915: Initialize pm_intr_keep
> during intel_irq_init for GuC) depending on the outcome of
> https://patchwork.freedesktop.org/series/20980/.

That failed, so blocker removed.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre