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

John.C.Harrison
2015-07-17T14:34:05Z

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@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);