[FOR_CI 07/14] drm/i915/tdr: Restart submission after engine reset

[Arun Siluvery]

We stop the engine during reset and recovery so after a successful reset,
restart submissions to elsp.

Also context events drive future resubmissions but in the current
implementation we drop the request that caused the hang and so we won't
receive completion interrupt for this request hence restart submission
explicity after reset.

Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c        | 17 +++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.h |  7 +++++++
 2 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index d4bdb82..b55dd0a 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1141,6 +1141,23 @@ int intel_execlists_reset_prepare(struct intel_engine_cs *engine)
 	return ret;
 }
 
+/**
+ * intel_execlists_restart_submission() - restarts elsp submissions after
+ * reset
+ *
+ * @engine: engine to be re-started
+ *
+ */
+void intel_execlists_restart_submission(struct intel_engine_cs *engine)
+{
+	if (list_empty(&engine->execlist_queue))
+		return;
+
+	spin_lock_bh(&engine->execlist_lock);
+	execlists_context_unqueue(engine);
+	spin_unlock_bh(&engine->execlist_lock);
+}
+
 static int intel_logical_ring_workarounds_emit(struct drm_i915_gem_request *req)
 {
 	int ret, i;
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index df7587a..2c9d94f 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -80,6 +80,13 @@ struct intel_ring_hangcheck {
 	enum intel_ring_hangcheck_action action;
 	int deadlock;
 	u32 instdone[I915_NUM_INSTDONE_REG];
+
+	/*
+	 * Last recorded ring head index.
+	 * This is only ever a ring index where as active
+	 * head may be a graphics address in a ring buffer
+	 */
+	u32 last_head;
 };
 
 struct intel_ringbuffer {
-- 
1.9.1