drm/irq: Add drm_crtc_vblank_reset

[firefly-linux-kernel-4.4.55.git] / drivers / gpu / drm / drm_irq.c

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 75647e7f012b303fee89d7e79cdc1e01d0645d05..e78a1f5cad9cdb189d597f35e64aedc1d0f80261 100644 (file)
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1225,6 +1225,38 @@ void drm_crtc_vblank_off(struct drm_crtc *crtc)
 }
 EXPORT_SYMBOL(drm_crtc_vblank_off);
 
+/**
+ * drm_crtc_vblank_reset - reset vblank state to off on a CRTC
+ * @crtc: CRTC in question
+ *
+ * Drivers can use this function to reset the vblank state to off at load time.
+ * Drivers should use this together with the drm_crtc_vblank_off() and
+ * drm_crtc_vblank_on() functions. The difference compared to
+ * drm_crtc_vblank_off() is that this function doesn't save the vblank counter
+ * and hence doesn't need to call any driver hooks.
+ */
+void drm_crtc_vblank_reset(struct drm_crtc *drm_crtc)
+{
+       struct drm_device *dev = drm_crtc->dev;
+       unsigned long irqflags;
+       int crtc = drm_crtc_index(drm_crtc);
+       struct drm_vblank_crtc *vblank = &dev->vblank[crtc];
+
+       spin_lock_irqsave(&dev->vbl_lock, irqflags);
+       /*
+        * Prevent subsequent drm_vblank_get() from enabling the vblank
+        * interrupt by bumping the refcount.
+        */
+       if (!vblank->inmodeset) {
+               atomic_inc(&vblank->refcount);
+               vblank->inmodeset = 1;
+       }
+       spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
+
+       WARN_ON(!list_empty(&dev->vblank_event_list));
+}
+EXPORT_SYMBOL(drm_crtc_vblank_reset);
+
 /**
  * drm_vblank_on - enable vblank events on a CRTC
  * @dev: DRM device