drm/i915: fix HW lockup due to missing RPS IRQ workaround on GEN6

In

commit dbea3cea
Author: Imre Deak <imre.deak@intel.com>
Date:   Mon Dec 15 18:59:28 2014 +0200

    drm/i915: sanitize RPS resetting during GPU reset

we disable RPS interrupts during GPU resetting, but don't apply the
necessary GEN6 HW workaround. This leads to a HW lockup during a
subsequent "looping batchbuffer" workload. This is triggered by the
testcase that submits exactly this kind of workload after a simulated
GPU reset. I'm not sure how likely the bug would have triggered
otherwise, since we would have applied the workaround anyway shortly
after the GPU reset, when enabling GT powersaving from the deferred
work.

This may also fix unrelated issues, since during driver loading /
suspending we also disable RPS interrupts and so we also had a short
window during the rest of the loading / resuming where a similar
workload could run without the workaround applied.

v2:
- separate the fix to route RPS interrupts to the CPU on GEN9 too
  to a separate patch (Daniel)
Bisected-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Testcase: igt/gem_reset_stats/ban-ctx-render
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87429Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -292,6 +292,21 @@ void gen6_enable_rps_interrupts(struct drm_device *dev)
 	spin_unlock_irq(&dev_priv->irq_lock);
 }
 
+u32 gen6_sanitize_rps_pm_mask(struct drm_i915_private *dev_priv, u32 mask)
+{
+	/*
+	 * IVB and SNB hard hangs on looping batchbuffer
+	 * if GEN6_PM_UP_EI_EXPIRED is masked.
+	 */
+	if (INTEL_INFO(dev_priv)->gen <= 7 && !IS_HASWELL(dev_priv))
+		mask &= ~GEN6_PM_RP_UP_EI_EXPIRED;
+
+	if (INTEL_INFO(dev_priv)->gen >= 8)
+		mask &= ~GEN8_PMINTR_REDIRECT_TO_NON_DISP;
+
+	return mask;
+}
+
 void gen6_disable_rps_interrupts(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -304,8 +319,7 @@ void gen6_disable_rps_interrupts(struct drm_device *dev)
 
 	spin_lock_irq(&dev_priv->irq_lock);
 
-	I915_WRITE(GEN6_PMINTRMSK, INTEL_INFO(dev_priv)->gen >= 8 ?
-		   ~GEN8_PMINTR_REDIRECT_TO_NON_DISP : ~0);
+	I915_WRITE(GEN6_PMINTRMSK, gen6_sanitize_rps_pm_mask(dev_priv, ~0));
 
 	__gen6_disable_pm_irq(dev_priv, dev_priv->pm_rps_events);
 	I915_WRITE(gen6_pm_ier(dev_priv), I915_READ(gen6_pm_ier(dev_priv)) &

drivers/gpu/drm/i915/intel_drv.h

@@ -794,6 +794,7 @@ void gen6_disable_pm_irq(struct drm_i915_private *dev_priv, uint32_t mask);
 void gen6_reset_rps_interrupts(struct drm_device *dev);
 void gen6_enable_rps_interrupts(struct drm_device *dev);
 void gen6_disable_rps_interrupts(struct drm_device *dev);
+u32 gen6_sanitize_rps_pm_mask(struct drm_i915_private *dev_priv, u32 mask);
 void intel_runtime_pm_disable_interrupts(struct drm_i915_private *dev_priv);
 void intel_runtime_pm_enable_interrupts(struct drm_i915_private *dev_priv);
 static inline bool intel_irqs_enabled(struct drm_i915_private *dev_priv)

drivers/gpu/drm/i915/intel_pm.c

@@ -4363,16 +4363,7 @@ static u32 gen6_rps_pm_mask(struct drm_i915_private *dev_priv, u8 val)
 	mask |= dev_priv->pm_rps_events & (GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED);
 	mask &= dev_priv->pm_rps_events;
 
-	/* IVB and SNB hard hangs on looping batchbuffer
-	 * if GEN6_PM_UP_EI_EXPIRED is masked.
-	 */
-	if (INTEL_INFO(dev_priv->dev)->gen <= 7 && !IS_HASWELL(dev_priv->dev))
-		mask |= GEN6_PM_RP_UP_EI_EXPIRED;
-
-	if (INTEL_INFO(dev_priv)->gen >= 8)
-		mask |= GEN8_PMINTR_REDIRECT_TO_NON_DISP;
-
-	return ~mask;
+	return gen6_sanitize_rps_pm_mask(dev_priv, ~mask);
 }
 
 /* gen6_set_rps is called to update the frequency request, but should also be