[RFC PATCH 1/6] drm: add helper for arming crtc completion event

[Andrzej Hajda]

A lot of drivers need to fire pageflip completion event at very next vblank
interrupt. The patch adds helper to perform this operation.
drm_crtc_arm_completion_event checks if there is an event to handle,
if vblank reference get succeeds it arms the event, otherwise it sends the
event immediately.

Signed-off-by: Andrzej Hajda <a.hajda at samsung.com>
---
 drivers/gpu/drm/drm_irq.c | 25 +++++++++++++++++++++++++
 include/drm/drm_irq.h     |  1 +
 2 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 77f357b..313d323 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1053,6 +1053,31 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
 EXPORT_SYMBOL(drm_crtc_send_vblank_event);
 
 /**
+ * drm_crtc_arm_completion_event - conditionally arm crtc completion event
+ * @crtc: the source CRTC of the completion event
+ *
+ * A lot of drivers need to fire pageflip completion event at very next vblank
+ * interrupt. This helper tries to arm the event in case of successful vblank
+ * get otherwise it sends the event immediately.
+ */
+void drm_crtc_arm_completion_event(struct drm_crtc *crtc)
+{
+	struct drm_pending_vblank_event *event = crtc->state->event;
+
+	if (event) {
+		crtc->state->event = NULL;
+
+		spin_lock_irq(&crtc->dev->event_lock);
+		if (drm_crtc_vblank_get(crtc) == 0)
+			drm_crtc_arm_vblank_event(crtc, event);
+		else
+			drm_crtc_send_vblank_event(crtc, event);
+		spin_unlock_irq(&crtc->dev->event_lock);
+	}
+}
+EXPORT_SYMBOL(drm_crtc_arm_completion_event);
+
+/**
  * drm_vblank_enable - enable the vblank interrupt on a CRTC
  * @dev: DRM device
  * @pipe: CRTC index
diff --git a/include/drm/drm_irq.h b/include/drm/drm_irq.h
index 2401b14..7bd9690 100644
--- a/include/drm/drm_irq.h
+++ b/include/drm/drm_irq.h
@@ -144,6 +144,7 @@ extern void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
 				       struct drm_pending_vblank_event *e);
 extern void drm_crtc_arm_vblank_event(struct drm_crtc *crtc,
 				      struct drm_pending_vblank_event *e);
+extern void drm_crtc_arm_completion_event(struct drm_crtc *crtc);
 extern bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe);
 extern bool drm_crtc_handle_vblank(struct drm_crtc *crtc);
 extern int drm_crtc_vblank_get(struct drm_crtc *crtc);
-- 
2.7.4