[Intel-gfx] [PATCH 1/2] drm/i915: Add new frontbuffer tracking interface to queue flush

[Jouni Högander]

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.

Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
---
 .../gpu/drm/i915/display/intel_frontbuffer.c  | 33 +++++++++++++++++++
 .../gpu/drm/i915/display/intel_frontbuffer.h  |  4 +++
 2 files changed, 37 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.c b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
index 17a7aa8b28c2..799f3f8a5d85 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.c
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.c
@@ -202,6 +202,39 @@ 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)
+{
+	unsigned int frontbuffer_bits;
+
+	if (!front)
+		return;
+
+	frontbuffer_bits = atomic_read(&front->bits);
+	if (!frontbuffer_bits)
+		return;
+
+	kref_get(&front->ref);
+	INIT_WORK(&front->flush_work, intel_frontbuffer_flush_work);
+	schedule_work(&front->flush_work);
+}
+
 static int frontbuffer_active(struct i915_active *ref)
 {
 	struct intel_frontbuffer *front =
diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.h b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
index 3c474ed937fb..11760b5ce9fa 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.h
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
@@ -47,6 +47,8 @@ struct intel_frontbuffer {
 	struct i915_active write;
 	struct drm_i915_gem_object *obj;
 	struct rcu_head rcu;
+
+	struct work_struct flush_work;
 };
 
 /*
@@ -163,6 +165,8 @@ 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