[Intel-gfx] [PATCH v4 3/4] drm/i915: Add new frontbuffer tracking interface to queue flush

["Jouni Högander" <jouni.hogander@intel.com>]

We want to wait dma fences in dirtyfb ioctl. As we don't want to make
dirtyfb ioctl as blocking call we need to use
dma_fence_add_callback. Callback used for dma_fence_add_callback is
called from atomic context. Due to this we need to add a new
frontbuffer tracking interface to queue flush.

v3:
 - Check schedule work success rather than work being pending
 - Init flush work when frontbuffer struct is initialized
v2: Check if flush work is already pending

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
---
 .../gpu/drm/i915/display/intel_frontbuffer.c  | 28 +++++++++++++++++++
 .../gpu/drm/i915/display/intel_frontbuffer.h  |  4 +++
 2 files changed, 32 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
index 54ddb69eca66..d5540c739404 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
@@ -203,6 +203,33 @@ void __intel_fb_flush(struct intel_frontbuffer *front,
 		frontbuffer_flush(i915, frontbuffer_bits, origin);
 }
 
+static void intel_frontbuffer_flush_work(struct work_struct *work)
+{
+	struct intel_frontbuffer *front =
+		container_of(work, struct intel_frontbuffer, flush_work);
+
+	i915_gem_object_flush_if_display(front->obj);
+	intel_frontbuffer_flush(front, ORIGIN_DIRTYFB);
+	intel_frontbuffer_put(front);
+}
+
+/**
+ * intel_frontbuffer_queue_flush - queue flushing frontbuffer object
+ * @front: GEM object to flush
+ *
+ * This function is targeted for our dirty callback for queueing flush when
+ * dma fence is signales
+ */
+void intel_frontbuffer_queue_flush(struct intel_frontbuffer *front)
+{
+	if (!front)
+		return;
+
+	kref_get(&front->ref);
+	if (!schedule_work(&front->flush_work))
+		intel_frontbuffer_put(front);
+}
+
 static int frontbuffer_active(struct i915_active *ref)
 {
 	struct intel_frontbuffer *front =
@@ -262,6 +289,7 @@ intel_frontbuffer_get(struct drm_i915_gem_object *obj)
 			 frontbuffer_active,
 			 frontbuffer_retire,
 			 I915_ACTIVE_RETIRE_SLEEPS);
+	INIT_WORK(&front->flush_work, intel_frontbuffer_flush_work);
 
 	spin_lock(&i915->display.fb_tracking.lock);
 	cur = i915_gem_object_set_frontbuffer(obj, front);
diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.h b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
index 72d89be3284b..abb51e8bb920 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.h
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
@@ -46,6 +46,8 @@ struct intel_frontbuffer {
 	struct i915_active write;
 	struct drm_i915_gem_object *obj;
 	struct rcu_head rcu;
+
+	struct work_struct flush_work;
 };
 
 /*
@@ -135,6 +137,8 @@ static inline void intel_frontbuffer_flush(struct intel_frontbuffer *front,
 	__intel_fb_flush(front, origin, frontbuffer_bits);
 }
 
+void intel_frontbuffer_queue_flush(struct intel_frontbuffer *front);
+
 void intel_frontbuffer_track(struct intel_frontbuffer *old,
 			     struct intel_frontbuffer *new,
 			     unsigned int frontbuffer_bits);
-- 
2.34.1