drm/i915: Include the last semaphore sync point in the error-state

Should be useful to know what the driver thought the other ring's seqno
was when it last used a semaphore.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -655,10 +655,12 @@ static void i915_ring_error_state(struct seq_file *m,
 	if (INTEL_INFO(dev)->gen >= 6) {
 		seq_printf(m, "  RC PSMI: 0x%08x\n", error->rc_psmi[ring]);
 		seq_printf(m, "  FAULT_REG: 0x%08x\n", error->fault_reg[ring]);
-		seq_printf(m, "  SYNC_0: 0x%08x\n",
-			   error->semaphore_mboxes[ring][0]);
-		seq_printf(m, "  SYNC_1: 0x%08x\n",
-			   error->semaphore_mboxes[ring][1]);
+		seq_printf(m, "  SYNC_0: 0x%08x [last synced 0x%08x]\n",
+			   error->semaphore_mboxes[ring][0],
+			   error->semaphore_seqno[ring][0]);
+		seq_printf(m, "  SYNC_1: 0x%08x [last synced 0x%08x]\n",
+			   error->semaphore_mboxes[ring][1],
+			   error->semaphore_seqno[ring][1]);
 	}
 	seq_printf(m, "  seqno: 0x%08x\n", error->seqno[ring]);
 	seq_printf(m, "  waiting: %s\n", yesno(error->waiting[ring]));

drivers/gpu/drm/i915/i915_drv.h

@@ -197,6 +197,7 @@ struct drm_i915_error_state {
 	u32 instdone[I915_NUM_RINGS];
 	u32 acthd[I915_NUM_RINGS];
 	u32 semaphore_mboxes[I915_NUM_RINGS][I915_NUM_RINGS - 1];
+	u32 semaphore_seqno[I915_NUM_RINGS][I915_NUM_RINGS - 1];
 	u32 rc_psmi[I915_NUM_RINGS]; /* sleep state */
 	/* our own tracking of ring head and tail */
 	u32 cpu_ring_head[I915_NUM_RINGS];

drivers/gpu/drm/i915/i915_irq.c

@@ -1120,6 +1120,8 @@ static void i915_record_ring_state(struct drm_device *dev,
 			= I915_READ(RING_SYNC_0(ring->mmio_base));
 		error->semaphore_mboxes[ring->id][1]
 			= I915_READ(RING_SYNC_1(ring->mmio_base));
+		error->semaphore_seqno[ring->id][0] = ring->sync_seqno[0];
+		error->semaphore_seqno[ring->id][1] = ring->sync_seqno[1];
 	}
 
 	if (INTEL_INFO(dev)->gen >= 4) {