[Intel-gfx] [PATCH 25/32] drm/i915: Convert trace-irq to the breadcrumb waiter

[Chris Wilson]

If we convert the tracing over from direct use of ring->irq_get() and
over to the breadcrumb infrastructure, we only have a single user of the
ring->irq_get and so we will be able to simplify the driver routines
(eliminating the redundant validation and irq refcounting).

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h          |  8 -------
 drivers/gpu/drm/i915/i915_gem.c          |  6 -----
 drivers/gpu/drm/i915/i915_trace.h        |  2 +-
 drivers/gpu/drm/i915/intel_breadcrumbs.c | 39 ++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.h  |  4 +++-
 5 files changed, 43 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 37f4ef59fb4a..dabfb043362f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3625,12 +3625,4 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
 			    schedule_timeout_uninterruptible(remaining_jiffies);
 	}
 }
-
-static inline void i915_trace_irq_get(struct intel_engine_cs *ring,
-				      struct drm_i915_gem_request *req)
-{
-	if (ring->trace_irq_req == NULL && ring->irq_get(ring))
-		i915_gem_request_assign(&ring->trace_irq_req, req);
-}
-
 #endif
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 78bcd231b100..fdd9dd5296e9 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2907,12 +2907,6 @@ i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
 		i915_gem_object_retire__read(obj, ring->id);
 	}
 
-	if (unlikely(ring->trace_irq_req &&
-		     i915_gem_request_completed(ring->trace_irq_req))) {
-		ring->irq_put(ring);
-		i915_gem_request_assign(&ring->trace_irq_req, NULL);
-	}
-
 	WARN_ON(i915_verify_lists(ring->dev));
 }
 
diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index efca75bcace3..628008e6c24f 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -503,7 +503,7 @@ TRACE_EVENT(i915_gem_ring_dispatch,
 			   __entry->ring = ring->id;
 			   __entry->seqno = i915_gem_request_get_seqno(req);
 			   __entry->flags = flags;
-			   i915_trace_irq_get(ring, req);
+			   intel_breadcrumbs_enable_trace(req);
 			   ),
 
 	    TP_printk("dev=%u, ring=%u, seqno=%u, flags=%x",
diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
index 69b966b4f71b..ea5ee3f7fe01 100644
--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
@@ -258,17 +258,56 @@ void intel_engine_remove_breadcrumb(struct intel_engine_cs *engine,
 	spin_unlock(&b->lock);
 }
 
+static void intel_breadcrumbs_tracer(struct work_struct *work)
+{
+	struct intel_breadcrumbs *b =
+		container_of(work, struct intel_breadcrumbs, trace);
+	struct intel_rps_client rps;
+
+	INIT_LIST_HEAD(&rps.link);
+
+	do {
+		struct drm_i915_gem_request *request;
+
+		spin_lock(&b->lock);
+		request = b->trace_request;
+		b->trace_request = NULL;
+		spin_unlock(&b->lock);
+		if (request == NULL)
+			return;
+
+		__i915_wait_request(request, true, NULL, &rps);
+		i915_gem_request_unreference__unlocked(request);
+	} while (1);
+}
+
+void intel_breadcrumbs_enable_trace(struct drm_i915_gem_request *request)
+{
+	struct intel_breadcrumbs *b = &request->ring->breadcrumbs;
+
+	spin_lock(&b->lock);
+	if (b->trace_request == NULL) {
+		b->trace_request = i915_gem_request_reference(request);
+		queue_work(system_long_wq, &b->trace);
+	}
+	spin_unlock(&b->lock);
+}
+
 void intel_engine_init_breadcrumbs(struct intel_engine_cs *engine)
 {
 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
 
 	spin_lock_init(&b->lock);
 	setup_timer(&b->fake_irq, intel_breadcrumbs_fake_irq, (unsigned long)b);
+	INIT_WORK(&b->trace, intel_breadcrumbs_tracer);
 }
 
 void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
 {
 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
 
+	cancel_work_sync(&b->trace);
+	i915_gem_request_unreference(b->trace_request);
+
 	del_timer_sync(&b->fake_irq);
 }
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index a35c17106f4b..0fd6395f1a1b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -182,6 +182,8 @@ struct  intel_engine_cs {
 		struct rb_root requests; /* sorted by retirement */
 		struct task_struct *first_waiter; /* bh for user interrupts */
 		struct timer_list fake_irq; /* used after a missed interrupt */
+		struct work_struct trace;
+		struct drm_i915_gem_request *trace_request;
 		bool irq_enabled;
 		bool rpm_wakelock;
 	} breadcrumbs;
@@ -198,7 +200,6 @@ struct  intel_engine_cs {
 
 	unsigned irq_refcount; /* protected by dev_priv->irq_lock */
 	u32		irq_enable_mask;	/* bitmask to enable ring interrupt */
-	struct drm_i915_gem_request *trace_irq_req;
 	bool __must_check (*irq_get)(struct intel_engine_cs *ring);
 	void		(*irq_put)(struct intel_engine_cs *ring);
 
@@ -555,6 +556,7 @@ bool intel_engine_add_breadcrumb(struct intel_engine_cs *engine,
 				 struct intel_breadcrumb *wait);
 void intel_engine_remove_breadcrumb(struct intel_engine_cs *engine,
 				    struct intel_breadcrumb *wait);
+void intel_breadcrumbs_enable_trace(struct drm_i915_gem_request *request);
 static inline bool intel_engine_has_waiter(struct intel_engine_cs *engine)
 {
 	return READ_ONCE(engine->breadcrumbs.first_waiter);
-- 
2.6.3