[Intel-gfx] [RFC 13/39] drm/i915: Added deferred work handler for scheduler

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

The scheduler needs to do interrupt triggered work that is too complex to do in
the interrupt handler. Thus it requires a deferred work handler to process this
work asynchronously.

Change-Id: I0f7cc2b6f034a50bf8f7e368b60ad8bafd00f993
For: VIZ-1587
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/i915_dma.c       |  3 +++
 drivers/gpu/drm/i915/i915_drv.h       | 10 ++++++++++
 drivers/gpu/drm/i915/i915_gem.c       |  2 ++
 drivers/gpu/drm/i915/i915_scheduler.c | 23 +++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_scheduler.h |  1 +
 5 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 0a25017..4d3370f 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1084,6 +1084,9 @@ int i915_driver_unload(struct drm_device *dev)
 	WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 	unregister_shrinker(&dev_priv->mm.shrinker);
 
+	/* Cancel the scheduler work handler, which should be idle now. */
+	cancel_work_sync(&dev_priv->mm.scheduler_work);
+
 	io_mapping_free(dev_priv->gtt.mappable);
 	arch_phys_wc_del(dev_priv->gtt.mtrr);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 58f53ec..2b3fab6 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1299,6 +1299,16 @@ struct i915_gem_mm {
 	struct delayed_work retire_work;
 
 	/**
+	 * New scheme is to get an interrupt after every work packet
+	 * in order to allow the low latency scheduling of pending
+	 * packets. The idea behind adding new packets to a pending
+	 * queue rather than directly into the hardware ring buffer
+	 * is to allow high priority packets to over take low priority
+	 * ones.
+	 */
+	struct work_struct scheduler_work;
+
+	/**
 	 * When we detect an idle GPU, we want to turn on
 	 * powersaving features. So once we see that there
 	 * are no more requests outstanding and no more
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e3c4032..77a3b27 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5631,6 +5631,8 @@ i915_gem_load(struct drm_device *dev)
 			  i915_gem_retire_work_handler);
 	INIT_DELAYED_WORK(&dev_priv->mm.idle_work,
 			  i915_gem_idle_work_handler);
+	INIT_WORK(&dev_priv->mm.scheduler_work,
+				i915_gem_scheduler_work_handler);
 	init_waitqueue_head(&dev_priv->gpu_error.reset_queue);
 
 	dev_priv->relative_constants_mode = I915_EXEC_CONSTANTS_REL_GENERAL;
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 50bcccb..3494fd5 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -407,12 +407,12 @@ int i915_scheduler_handle_irq(struct intel_engine_cs *ring)
 	i915_scheduler_seqno_complete(ring, seqno);
 	spin_unlock_irqrestore(&scheduler->lock, flags);
 
-	/* XXX: Need to also call i915_scheduler_remove() via work handler. */
+	queue_work(dev_priv->wq, &dev_priv->mm.scheduler_work);
 
 	return 0;
 }
 
-int i915_scheduler_remove(struct intel_engine_cs *ring)
+static int i915_scheduler_remove(struct intel_engine_cs *ring)
 {
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
 	struct i915_scheduler   *scheduler = dev_priv->scheduler;
@@ -531,6 +531,25 @@ int i915_scheduler_remove(struct intel_engine_cs *ring)
 	return ret;
 }
 
+void i915_gem_scheduler_work_handler(struct work_struct *work)
+{
+	struct intel_engine_cs  *ring;
+	struct drm_i915_private *dev_priv;
+	struct drm_device       *dev;
+	int                     i;
+
+	dev_priv = container_of(work, struct drm_i915_private, mm.scheduler_work);
+	dev = dev_priv->dev;
+
+	mutex_lock(&dev->struct_mutex);
+
+	for_each_ring(ring, dev_priv, i) {
+		i915_scheduler_remove(ring);
+	}
+
+	mutex_unlock(&dev->struct_mutex);
+}
+
 static void i915_scheduler_priority_bump_clear(struct i915_scheduler *scheduler)
 {
 	struct i915_scheduler_queue_entry *node;
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index fbb6f7b..15878a4 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -90,6 +90,7 @@ int         i915_scheduler_closefile(struct drm_device *dev,
 				     struct drm_file *file);
 int         i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe);
 int         i915_scheduler_handle_irq(struct intel_engine_cs *ring);
+void        i915_gem_scheduler_work_handler(struct work_struct *work);
 bool        i915_scheduler_is_request_tracked(struct drm_i915_gem_request *req,
 					      bool *completed, bool *busy);
 
-- 
1.9.1