drm/i915: Reset the hangcheck timestamp before repeating a seqno

In the unusual circumstance where we reuse a seqno (for example, in
igt), make sure that we reset the hangcheck timestamp before it sees the
same seqno again.

References: https://bugs.freedesktop.org/show_bug.cgi?id=106215
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180502220313.6459-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_request.c

@@ -223,6 +223,7 @@ static int reset_all_global_seqno(struct drm_i915_private *i915, u32 seqno)
 		if (!i915_seqno_passed(seqno, engine->timeline.seqno)) {
 			/* Flush any waiters before we reuse the seqno */
 			intel_engine_disarm_breadcrumbs(engine);
+			intel_engine_init_hangcheck(engine);
 			GEM_BUG_ON(!list_empty(&engine->breadcrumbs.signals));
 		}
 

drivers/gpu/drm/i915/intel_hangcheck.c

@@ -452,6 +452,7 @@ static void i915_hangcheck_elapsed(struct work_struct *work)
 void intel_engine_init_hangcheck(struct intel_engine_cs *engine)
 {
 	memset(&engine->hangcheck, 0, sizeof(engine->hangcheck));
+	engine->hangcheck.action_timestamp = jiffies;
 }
 
 void intel_hangcheck_init(struct drm_i915_private *i915)