[Intel-gfx] [PATCH] drm/i915: Inspect subunit states on hangcheck

[Mika Kuoppala]

If head seems stuck and engine in question is rcs,
inspect subunit state transitions before deciding that
this really is a hang instead of limited progress.

References: https://bugs.freedesktop.org/show_bug.cgi?id=93029
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon at intel.com>
Cc: Daniel Vetter <daniel at ffwll.ch>
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_irq.c         | 49 +++++++++++++++++++++++++++++----
 drivers/gpu/drm/i915/intel_ringbuffer.h |  1 +
 2 files changed, 45 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index e88d692..e6ae54f 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2913,13 +2913,31 @@ static void semaphore_clear_deadlocks(struct drm_i915_private *dev_priv)
 		ring->hangcheck.deadlock = 0;
 }
 
-static enum intel_ring_hangcheck_action
-ring_stuck(struct intel_engine_cs *ring, u64 acthd)
+static bool subunits_stuck(struct intel_engine_cs *ring)
 {
-	struct drm_device *dev = ring->dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 tmp;
+	int i;
+	u32 instdone[I915_NUM_INSTDONE_REG];
+	bool stuck;
+
+	if (ring->id != RCS)
+		return true;
+
+	i915_get_extra_instdone(ring->dev, instdone);
 
+	stuck = true;
+	for (i = 0; i < I915_NUM_INSTDONE_REG; i++) {
+		if (instdone[i] != ring->hangcheck.instdone[i])
+			stuck = false;
+
+		ring->hangcheck.instdone[i] = instdone[i];
+	}
+
+	return stuck;
+}
+
+static enum intel_ring_hangcheck_action
+head_stuck(struct intel_engine_cs *ring, u64 acthd)
+{
 	if (acthd != ring->hangcheck.acthd) {
 		if (acthd > ring->hangcheck.max_acthd) {
 			ring->hangcheck.max_acthd = acthd;
@@ -2929,6 +2947,24 @@ ring_stuck(struct intel_engine_cs *ring, u64 acthd)
 		return HANGCHECK_ACTIVE_LOOP;
 	}
 
+	if (!subunits_stuck(ring))
+		return HANGCHECK_ACTIVE_LOOP;
+
+	return HANGCHECK_HUNG;
+}
+
+static enum intel_ring_hangcheck_action
+ring_stuck(struct intel_engine_cs *ring, u64 acthd)
+{
+	struct drm_device *dev = ring->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	enum intel_ring_hangcheck_action ha;
+	u32 tmp;
+
+	ha = head_stuck(ring, acthd);
+	if (ha != HANGCHECK_HUNG)
+		return ha;
+
 	if (IS_GEN2(dev))
 		return HANGCHECK_HUNG;
 
@@ -3064,6 +3100,9 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
 				ring->hangcheck.score--;
 
 			ring->hangcheck.acthd = ring->hangcheck.max_acthd = 0;
+
+			memset(ring->hangcheck.instdone, 0,
+			       sizeof(ring->hangcheck.instdone));
 		}
 
 		ring->hangcheck.seqno = seqno;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 5d1eb20..b8fe92e 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -93,6 +93,7 @@ struct intel_ring_hangcheck {
 	int score;
 	enum intel_ring_hangcheck_action action;
 	int deadlock;
+	u32 instdone[I915_NUM_INSTDONE_REG];
 };
 
 struct intel_ringbuffer {
-- 
2.5.0