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, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 49574ffe54bc..7349d9258191 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 {