drm/i915: Inspect subunit states on hangcheck

If head seems stuck and engine in question is rcs,
inspect subunit state transitions from undone to done,
before deciding that this really is a hang instead of limited
progress. Only account the transitions of subunits from
undone to done once, to prevent unstable subunit states
to keep us falsely active.

As this adds one extra steps to hangcheck heuristics,
before hang is declared, it adds 1500ms to to detect hang
for render ring to a total of 7500ms. We could sample
the subunit states on first head stuck condition but
decide not to do so only in order to mimic old behaviour. This
way the check order of promotion from seqno > atchd > instdone
is consistently done.

v2: Deal with unstable done states (Arun)
    Clear instdone progress on head and seqno movement (Chris)
    Report raw and accumulated instdone's in in debugfs (Chris)
    Return HANGCHECK_ACTIVE on undone->done

References: https://bugs.freedesktop.org/show_bug.cgi?id=93029
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Arun Siluvery <arun.siluvery@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448985372-19535-1-git-send-email-mika.kuoppala@intel.com

1 files changed, 19 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 3b05bd189eab..e3377abc0d4d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1331,7 +1331,8 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
 	struct intel_engine_cs *ring;
 	u64 acthd[I915_NUM_RINGS];
 	u32 seqno[I915_NUM_RINGS];
-	int i;
+	u32 instdone[I915_NUM_INSTDONE_REG];
+	int i, j;
 
 	if (!i915.enable_hangcheck) {
 		seq_printf(m, "Hangcheck disabled\n");
@@ -1345,6 +1346,8 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
 		acthd[i] = intel_ring_get_active_head(ring);
 	}
 
+	i915_get_extra_instdone(dev, instdone);
+
 	intel_runtime_pm_put(dev_priv);
 
 	if (delayed_work_pending(&dev_priv->gpu_error.hangcheck_work)) {
@@ -1365,6 +1368,21 @@ static int i915_hangcheck_info(struct seq_file *m, void *unused)
 			   (long long)ring->hangcheck.max_acthd);
 		seq_printf(m, "\tscore = %d\n", ring->hangcheck.score);
 		seq_printf(m, "\taction = %d\n", ring->hangcheck.action);
+
+		if (ring->id == RCS) {
+			seq_puts(m, "\tinstdone read =");
+
+			for (j = 0; j < I915_NUM_INSTDONE_REG; j++)
+				seq_printf(m, " 0x%08x", instdone[j]);
+
+			seq_puts(m, "\n\tinstdone accu =");
+
+			for (j = 0; j < I915_NUM_INSTDONE_REG; j++)
+				seq_printf(m, " 0x%08x",
+					   ring->hangcheck.instdone[j]);
+
+			seq_puts(m, "\n");
+		}
 	}
 
 	return 0;