[Intel-gfx] [PATCH v4 13/38] 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 such tasks asynchronously.

v2: Updated to reduce mutex lock usage. The lock is now only held for
the minimum time within the remove function rather than for the whole
of the worker thread's operation.

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 | 21 +++++++++++++++++++--
 drivers/gpu/drm/i915/i915_scheduler.h |  1 +
 5 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index c2f9c03..8c9246f 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1149,6 +1149,9 @@ 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 ac4d44b..31bf349 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1285,6 +1285,16 @@ 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 3d109b4..f396393 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5354,6 +5354,8 @@ 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 ac0a6172..c94c941 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -389,10 +389,12 @@ bool i915_scheduler_notify_request(struct drm_i915_gem_request *req)
  */
 void i915_scheduler_wakeup(struct drm_device *dev)
 {
-	/* XXX: Need to call i915_scheduler_remove() via work handler. */
+	struct drm_i915_private *dev_priv  = to_i915(dev);
+
+	queue_work(dev_priv->wq, &dev_priv->mm.scheduler_work);
 }
 
-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;
@@ -519,6 +521,21 @@ 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;
+
+	for_each_ring(ring, dev_priv, i) {
+		i915_scheduler_remove(ring);
+	}
+}
+
 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 9f54786..56f68e5 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -91,5 +91,6 @@ int         i915_scheduler_closefile(struct drm_device *dev,
 int         i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe);
 bool        i915_scheduler_notify_request(struct drm_i915_gem_request *req);
 void        i915_scheduler_wakeup(struct drm_device *dev);
+void        i915_gem_scheduler_work_handler(struct work_struct *work);
 
 #endif  /* _I915_SCHEDULER_H_ */
-- 
1.9.1