[PATCH 1/4] drm/i915: Unify execlist and legacy request life-cycles

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There is a desire to simplify the i915 driver by reducing the number of
different code paths introduced by the LRC / execlists support.  As the
execlists request is now part of the gem request it is possible and
desirable to unify the request life-cycles for execlist and legacy
requests.

Added a context complete flag to a request which gets set during the
context switch interrupt.

Added a function i915_gem_request_retireable().  A request is considered
retireable if its seqno passed (i.e. the request has completed) and either
it was never submitted to the ELSP or its context completed.  This ensures
that context save is carried out before the last request for a context is
considered retireable.  retire_requests_ring() now uses
i915_gem_request_retireable() rather than request_complete() when deciding
which requests to retire. Requests that were not waiting for a context
switch interrupt (either as a result of being merged into a following
request or by being a legacy request) will be considered retireable as
soon as their seqno has passed.

Removed the extra request reference held for the execlist request.

Removed intel_execlists_retire_requests() and all references to
intel_engine_cs.execlist_retired_req_list.

Moved context unpinning into retire_requests_ring() for now.  Further work
is pending for the context pinning - this patch should allow us to use the
active list to track context and ring buffer objects later.

Changed gen8_cs_irq_handler() so that notify_ring() is called when
contexts complete as well as when a user interrupt occurs so that
notification happens when a request is complete and context save has
finished.

v2: Rebase over the read-read optimisation changes

v3: Reworked IRQ handler after removing IRQ handler cleanup patch

v4: Fixed various pin leaks

Issue: VIZ-4277
Signed-off-by: Thomas Daniel <thomas.daniel@xxxxxxxxx>
Signed-off-by: Nick Hoath <nicholas.hoath@xxxxxxxxx>
---
 drivers/gpu/drm/i915/i915_drv.h         |  6 +++
 drivers/gpu/drm/i915/i915_gem.c         | 67 +++++++++++++++++++++------
 drivers/gpu/drm/i915/i915_irq.c         | 81 +++++++++++++++++++++------------
 drivers/gpu/drm/i915/intel_lrc.c        | 43 +++--------------
 drivers/gpu/drm/i915/intel_lrc.h        |  2 +-
 drivers/gpu/drm/i915/intel_ringbuffer.h |  1 -
 6 files changed, 118 insertions(+), 82 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index fbf0ae9..3d217f9 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2262,6 +2262,12 @@ struct drm_i915_gem_request {
 	/** Execlists no. of times this request has been sent to the ELSP */
 	int elsp_submitted;
 
+	/**
+	 * Execlists: whether this requests's context has completed after
+	 * submission to the ELSP
+	 */
+	bool ctx_complete;
+
 };
 
 int i915_gem_request_alloc(struct intel_engine_cs *ring,
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 52642af..fc82171 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1386,6 +1386,24 @@ __i915_gem_request_retire__upto(struct drm_i915_gem_request *req)
 				       typeof(*tmp), list);
 
 		i915_gem_request_retire(tmp);
+
+		if (i915.enable_execlists) {
+			struct intel_context *ctx = tmp->ctx;
+			struct drm_i915_private *dev_priv =
+				engine->dev->dev_private;
+			unsigned long flags;
+			struct drm_i915_gem_object *ctx_obj =
+				ctx->engine[engine->id].state;
+
+			spin_lock_irqsave(&engine->execlist_lock, flags);
+
+			if (ctx_obj && (ctx != engine->default_context))
+				intel_lr_context_unpin(tmp);
+
+			intel_runtime_pm_put(dev_priv);
+			spin_unlock_irqrestore(&engine->execlist_lock, flags);
+		}
+
 	} while (tmp != req);
 
 	WARN_ON(i915_verify_lists(engine->dev));
@@ -2359,6 +2377,12 @@ void i915_vma_move_to_active(struct i915_vma *vma,
 	list_move_tail(&vma->mm_list, &vma->vm->active_list);
 }
 
+static bool i915_gem_request_retireable(struct drm_i915_gem_request *req)
+{
+	return (i915_gem_request_completed(req, true) &&
+		(!req->elsp_submitted || req->ctx_complete));
+}
+
 static void
 i915_gem_object_retire__write(struct drm_i915_gem_object *obj)
 {
@@ -2829,10 +2853,28 @@ i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
 					   struct drm_i915_gem_request,
 					   list);
 
-		if (!i915_gem_request_completed(request, true))
+		if (!i915_gem_request_retireable(request))
 			break;
 
 		i915_gem_request_retire(request);
+
+		if (i915.enable_execlists) {
+			struct intel_context *ctx = request->ctx;
+			struct drm_i915_private *dev_priv =
+				ring->dev->dev_private;
+			unsigned long flags;
+			struct drm_i915_gem_object *ctx_obj =
+				ctx->engine[ring->id].state;
+
+			spin_lock_irqsave(&ring->execlist_lock, flags);
+
+			if (ctx_obj && (ctx != ring->default_context))
+				intel_lr_context_unpin(request);
+
+			intel_runtime_pm_put(dev_priv);
+			spin_unlock_irqrestore(&ring->execlist_lock, flags);
+		}
+
 	}
 
 	/* Move any buffers on the active list that are no longer referenced
@@ -2848,12 +2890,14 @@ i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
 
 		if (!list_empty(&obj->last_read_req[ring->id]->list))
 			break;
+		if (!i915_gem_request_retireable(obj->last_read_req[ring->id]))
+			break;
 
 		i915_gem_object_retire__read(obj, ring->id);
 	}
 
 	if (unlikely(ring->trace_irq_req &&
-		     i915_gem_request_completed(ring->trace_irq_req, true))) {
+		     i915_gem_request_retireable(ring->trace_irq_req))) {
 		ring->irq_put(ring);
 		i915_gem_request_assign(&ring->trace_irq_req, NULL);
 	}
@@ -2872,15 +2916,6 @@ i915_gem_retire_requests(struct drm_device *dev)
 	for_each_ring(ring, dev_priv, i) {
 		i915_gem_retire_requests_ring(ring);
 		idle &= list_empty(&ring->request_list);
-		if (i915.enable_execlists) {
-			unsigned long flags;
-
-			spin_lock_irqsave(&ring->execlist_lock, flags);
-			idle &= list_empty(&ring->execlist_queue);
-			spin_unlock_irqrestore(&ring->execlist_lock, flags);
-
-			intel_execlists_retire_requests(ring);
-		}
 	}
 
 	if (idle)
@@ -2956,12 +2991,14 @@ i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
 		if (req == NULL)
 			continue;
 
-		if (list_empty(&req->list))
-			goto retire;
+		if (list_empty(&req->list)) {
+			if (i915_gem_request_retireable(req))
+				i915_gem_object_retire__read(obj, i);
+			continue;
+		}
 
-		if (i915_gem_request_completed(req, true)) {
+		if (i915_gem_request_retireable(req)) {
 			__i915_gem_request_retire__upto(req);
-retire:
 			i915_gem_object_retire__read(obj, i);
 		}
 	}
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 8ca772d..ebbafac 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1291,66 +1291,91 @@ static irqreturn_t gen8_gt_irq_handler(struct drm_i915_private *dev_priv,
 				       u32 master_ctl)
 {
 	irqreturn_t ret = IRQ_NONE;
+	bool need_notify;
 
 	if (master_ctl & (GEN8_GT_RCS_IRQ | GEN8_GT_BCS_IRQ)) {
-		u32 tmp = I915_READ_FW(GEN8_GT_IIR(0));
-		if (tmp) {
-			I915_WRITE_FW(GEN8_GT_IIR(0), tmp);
+		u32 iir = I915_READ_FW(GEN8_GT_IIR(0));
+
+		if (iir) {
+			I915_WRITE_FW(GEN8_GT_IIR(0), iir);
 			ret = IRQ_HANDLED;
 
-			if (tmp & (GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT))
-				intel_lrc_irq_handler(&dev_priv->ring[RCS]);
-			if (tmp & (GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT))
+			need_notify = false;
+			if (iir & (GT_CONTEXT_SWITCH_INTERRUPT <<
+					GEN8_RCS_IRQ_SHIFT))
+				need_notify = intel_lrc_irq_handler(
+						&dev_priv->ring[RCS]);
+			if (iir & (GT_RENDER_USER_INTERRUPT <<
+					GEN8_RCS_IRQ_SHIFT) || need_notify)
 				notify_ring(&dev_priv->ring[RCS]);
 
-			if (tmp & (GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT))
-				intel_lrc_irq_handler(&dev_priv->ring[BCS]);
-			if (tmp & (GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT))
+			need_notify = false;
+			if (iir & (GT_CONTEXT_SWITCH_INTERRUPT <<
+					GEN8_BCS_IRQ_SHIFT))
+				need_notify = intel_lrc_irq_handler(
+						&dev_priv->ring[BCS]);
+			if (iir & (GT_RENDER_USER_INTERRUPT <<
+					GEN8_BCS_IRQ_SHIFT) || need_notify)
 				notify_ring(&dev_priv->ring[BCS]);
 		} else
 			DRM_ERROR("The master control interrupt lied (GT0)!\n");
 	}
 
 	if (master_ctl & (GEN8_GT_VCS1_IRQ | GEN8_GT_VCS2_IRQ)) {
-		u32 tmp = I915_READ_FW(GEN8_GT_IIR(1));
-		if (tmp) {
-			I915_WRITE_FW(GEN8_GT_IIR(1), tmp);
+		u32 iir = I915_READ_FW(GEN8_GT_IIR(1));
+
+		if (iir) {
+			I915_WRITE_FW(GEN8_GT_IIR(1), iir);
 			ret = IRQ_HANDLED;
 
-			if (tmp & (GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS1_IRQ_SHIFT))
-				intel_lrc_irq_handler(&dev_priv->ring[VCS]);
-			if (tmp & (GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT))
+			need_notify = false;
+			if (iir & (GT_CONTEXT_SWITCH_INTERRUPT <<
+					GEN8_VCS1_IRQ_SHIFT))
+				need_notify = intel_lrc_irq_handler(
+						&dev_priv->ring[VCS]);
+			if (iir & (GT_RENDER_USER_INTERRUPT <<
+					GEN8_VCS1_IRQ_SHIFT) || need_notify)
 				notify_ring(&dev_priv->ring[VCS]);
 
-			if (tmp & (GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VCS2_IRQ_SHIFT))
-				intel_lrc_irq_handler(&dev_priv->ring[VCS2]);
-			if (tmp & (GT_RENDER_USER_INTERRUPT << GEN8_VCS2_IRQ_SHIFT))
+			need_notify = false;
+			if (iir & (GT_CONTEXT_SWITCH_INTERRUPT <<
+					GEN8_VCS2_IRQ_SHIFT))
+				need_notify = intel_lrc_irq_handler(
+						&dev_priv->ring[VCS2]);
+			if (iir & (GT_RENDER_USER_INTERRUPT <<
+					GEN8_VCS2_IRQ_SHIFT) || need_notify)
 				notify_ring(&dev_priv->ring[VCS2]);
 		} else
 			DRM_ERROR("The master control interrupt lied (GT1)!\n");
 	}
 
 	if (master_ctl & GEN8_GT_VECS_IRQ) {
-		u32 tmp = I915_READ_FW(GEN8_GT_IIR(3));
-		if (tmp) {
-			I915_WRITE_FW(GEN8_GT_IIR(3), tmp);
+		u32 iir = I915_READ_FW(GEN8_GT_IIR(3));
+
+		if (iir) {
+			I915_WRITE_FW(GEN8_GT_IIR(3), iir);
 			ret = IRQ_HANDLED;
 
-			if (tmp & (GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT))
-				intel_lrc_irq_handler(&dev_priv->ring[VECS]);
-			if (tmp & (GT_RENDER_USER_INTERRUPT << GEN8_VECS_IRQ_SHIFT))
+			need_notify = false;
+			if (iir & (GT_CONTEXT_SWITCH_INTERRUPT <<
+					GEN8_VECS_IRQ_SHIFT))
+				need_notify = intel_lrc_irq_handler(
+						&dev_priv->ring[VECS]);
+			if (iir & (GT_RENDER_USER_INTERRUPT <<
+					GEN8_VECS_IRQ_SHIFT) || need_notify)
 				notify_ring(&dev_priv->ring[VECS]);
 		} else
 			DRM_ERROR("The master control interrupt lied (GT3)!\n");
 	}
 
 	if (master_ctl & GEN8_GT_PM_IRQ) {
-		u32 tmp = I915_READ_FW(GEN8_GT_IIR(2));
-		if (tmp & dev_priv->pm_rps_events) {
+		u32 iir = I915_READ_FW(GEN8_GT_IIR(2));
+
+		if (iir & dev_priv->pm_rps_events) {
 			I915_WRITE_FW(GEN8_GT_IIR(2),
-				      tmp & dev_priv->pm_rps_events);
+				      iir & dev_priv->pm_rps_events);
 			ret = IRQ_HANDLED;
-			gen6_rps_irq_handler(dev_priv, tmp);
+			gen6_rps_irq_handler(dev_priv, iir);
 		} else
 			DRM_ERROR("The master control interrupt lied (PM)!\n");
 	}
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 825fa7a..e8f5b6c 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -426,9 +426,8 @@ static void execlists_context_unqueue(struct intel_engine_cs *ring)
 			/* Same ctx: ignore first request, as second request
 			 * will update tail past first request's workload */
 			cursor->elsp_submitted = req0->elsp_submitted;
+			req0->elsp_submitted = 0;
 			list_del(&req0->execlist_link);
-			list_add_tail(&req0->execlist_link,
-				&ring->execlist_retired_req_list);
 			req0 = cursor;
 		} else {
 			req1 = cursor;
@@ -478,11 +477,9 @@ static bool execlists_check_remove_request(struct intel_engine_cs *ring,
 		if (intel_execlists_ctx_id(ctx_obj) == request_id) {
 			WARN(head_req->elsp_submitted == 0,
 			     "Never submitted head request\n");
-
 			if (--head_req->elsp_submitted <= 0) {
+				head_req->ctx_complete = 1;
 				list_del(&head_req->execlist_link);
-				list_add_tail(&head_req->execlist_link,
-					&ring->execlist_retired_req_list);
 				return true;
 			}
 		}
@@ -497,8 +494,9 @@ static bool execlists_check_remove_request(struct intel_engine_cs *ring,
  *
  * Check the unread Context Status Buffers and manage the submission of new
  * contexts to the ELSP accordingly.
+ * @return whether a context completed
  */
-void intel_lrc_irq_handler(struct intel_engine_cs *ring)
+bool intel_lrc_irq_handler(struct intel_engine_cs *ring)
 {
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
 	u32 status_pointer;
@@ -558,6 +556,8 @@ void intel_lrc_irq_handler(struct intel_engine_cs *ring)
 		   _MASKED_FIELD(GEN8_CSB_PTR_MASK << 8,
 				 ((u32)ring->next_context_status_buffer &
 				  GEN8_CSB_PTR_MASK) << 8));
+
+	return (submit_contexts != 0);
 }
 
 static int execlists_context_queue(struct drm_i915_gem_request *request)
@@ -569,8 +569,6 @@ static int execlists_context_queue(struct drm_i915_gem_request *request)
 	if (request->ctx != ring->default_context)
 		intel_lr_context_pin(request);
 
-	i915_gem_request_reference(request);
-
 	spin_lock_irq(&ring->execlist_lock);
 
 	list_for_each_entry(cursor, &ring->execlist_queue, execlist_link)
@@ -588,8 +586,6 @@ static int execlists_context_queue(struct drm_i915_gem_request *request)
 			WARN(tail_req->elsp_submitted != 0,
 				"More than 2 already-submitted reqs queued\n");
 			list_del(&tail_req->execlist_link);
-			list_add_tail(&tail_req->execlist_link,
-				&ring->execlist_retired_req_list);
 		}
 	}
 
@@ -958,32 +954,6 @@ int intel_execlists_submission(struct i915_execbuffer_params *params,
 	return 0;
 }
 
-void intel_execlists_retire_requests(struct intel_engine_cs *ring)
-{
-	struct drm_i915_gem_request *req, *tmp;
-	struct list_head retired_list;
-
-	WARN_ON(!mutex_is_locked(&ring->dev->struct_mutex));
-	if (list_empty(&ring->execlist_retired_req_list))
-		return;
-
-	INIT_LIST_HEAD(&retired_list);
-	spin_lock_irq(&ring->execlist_lock);
-	list_replace_init(&ring->execlist_retired_req_list, &retired_list);
-	spin_unlock_irq(&ring->execlist_lock);
-
-	list_for_each_entry_safe(req, tmp, &retired_list, execlist_link) {
-		struct intel_context *ctx = req->ctx;
-		struct drm_i915_gem_object *ctx_obj =
-				ctx->engine[ring->id].state;
-
-		if (ctx_obj && (ctx != ring->default_context))
-			intel_lr_context_unpin(req);
-		list_del(&req->execlist_link);
-		i915_gem_request_unreference(req);
-	}
-}
-
 void intel_logical_ring_stop(struct intel_engine_cs *ring)
 {
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
@@ -1938,7 +1908,6 @@ static int logical_ring_init(struct drm_device *dev, struct intel_engine_cs *rin
 	init_waitqueue_head(&ring->irq_queue);
 
 	INIT_LIST_HEAD(&ring->execlist_queue);
-	INIT_LIST_HEAD(&ring->execlist_retired_req_list);
 	spin_lock_init(&ring->execlist_lock);
 
 	ret = i915_cmd_parser_init_ring(ring);
diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
index 4e60d54..e6a4900 100644
--- a/drivers/gpu/drm/i915/intel_lrc.h
+++ b/drivers/gpu/drm/i915/intel_lrc.h
@@ -95,7 +95,7 @@ int intel_execlists_submission(struct i915_execbuffer_params *params,
 			       struct list_head *vmas);
 u32 intel_execlists_ctx_id(struct drm_i915_gem_object *ctx_obj);
 
-void intel_lrc_irq_handler(struct intel_engine_cs *ring);
+bool intel_lrc_irq_handler(struct intel_engine_cs *ring);
 void intel_execlists_retire_requests(struct intel_engine_cs *ring);
 
 #endif /* _INTEL_LRC_H_ */
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 49fa41d..d99b167 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -264,7 +264,6 @@ struct  intel_engine_cs {
 	/* Execlists */
 	spinlock_t execlist_lock;
 	struct list_head execlist_queue;
-	struct list_head execlist_retired_req_list;
 	u8 next_context_status_buffer;
 	u32             irq_keep_mask; /* bitmask for interrupts that should not be masked */
 	int		(*emit_request)(struct drm_i915_gem_request *request);
-- 
1.9.1

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