[PATCH 4/4] drm: wait for vblank if pending vblank work

[Chaitanya Kumar Borah]

Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>
---
 drivers/gpu/drm/drm_vblank_work.c            | 15 ++++++++++++++-
 drivers/gpu/drm/i915/display/intel_display.c |  5 ++++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank_work.c b/drivers/gpu/drm/drm_vblank_work.c
index 83a81a5e8280..cd53c15ceb08 100644
--- a/drivers/gpu/drm/drm_vblank_work.c
+++ b/drivers/gpu/drm/drm_vblank_work.c
@@ -246,7 +246,7 @@ void drm_vblank_work_flush_all(struct drm_crtc *crtc)
 
 	spin_lock_irq(&dev->event_lock);
 	wait_event_lock_irq(vblank->work_wait_queue,
-			    !waitqueue_active(&vblank->work_wait_queue),
+			    no_pending_work_for_current_vblank(vblank)
 			    dev->event_lock);
 	spin_unlock_irq(&dev->event_lock);
 
@@ -254,6 +254,19 @@ void drm_vblank_work_flush_all(struct drm_crtc *crtc)
 }
 EXPORT_SYMBOL(drm_vblank_work_flush_all);
 
+static bool pending_vblank_work(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_vblank_crtc *vblank = &dev->vblank[drm_crtc_index(crtc)];
+	bool is_empty = false;
+
+	spin_lock_irq(&dev->event_lock);
+	is_empty = list_empty(&vblank->pending_work);
+	spin_unlock_irq(&dev->event_lock);
+
+	return is_empty;
+}
+EXPORT_SYMBOL(pending_vblank_work);
 /**
  * drm_vblank_work_init - initialize a vblank work item
  * @work: vblank work item
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 120ca76d1215..f42a41426f85 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -6925,7 +6925,10 @@ static void intel_commit_modeset_disables(struct intel_atomic_state *state)
 
 		intel_crtc_disable_planes(state, crtc);
 
-		drm_vblank_work_flush_all(&crtc->base);
+		if(pending_vblank_work(crtc)) {
+			intel_crtc_wait_for_next_vblank(crtc);
+			drm_vblank_work_flush_all(&crtc->base);
+		}
 	}
 
 	/* Only disable port sync and MST slaves */
-- 
2.25.1