drm/rockchip: Do not enable vblank without event

Originally we needed to enable vblank for any atomic commit to kick the
PSR machine, but that was changed and we no longer need to do so from
a vblank interrupt. Let's return to original behavior of enabling
vblank only if it is really necessary.

This essentially reverts commit 5b680403 ("drm/rockchip: Enable
vblank without event").
Signed-off-by: Tomasz Figa <tfiga@chromium.org>

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -116,7 +116,6 @@ struct vop {
 	struct device *dev;
 	struct drm_device *drm_dev;
 	bool is_enabled;
-	bool vblank_active;
 
 	/* mutex vsync_ work */
 	struct mutex vsync_mutex;
@@ -1131,11 +1130,10 @@ static void vop_crtc_atomic_begin(struct drm_crtc *crtc,
 	rockchip_drm_psr_flush(crtc);
 
 	spin_lock_irq(&crtc->dev->event_lock);
-	vop->vblank_active = true;
-	WARN_ON(drm_crtc_vblank_get(crtc) != 0);
-	WARN_ON(vop->event);
-
 	if (crtc->state->event) {
+		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+		WARN_ON(vop->event);
+
 		vop->event = crtc->state->event;
 		crtc->state->event = NULL;
 	}
@@ -1232,12 +1230,8 @@ static void vop_handle_vblank(struct vop *vop)
 	spin_lock_irqsave(&drm->event_lock, flags);
 	if (vop->event) {
 		drm_crtc_send_vblank_event(crtc, vop->event);
-		vop->event = NULL;
-
-	}
-	if (vop->vblank_active) {
-		vop->vblank_active = false;
 		drm_crtc_vblank_put(crtc);
+		vop->event = NULL;
 	}
 	spin_unlock_irqrestore(&drm->event_lock, flags);
 
@@ -1514,7 +1508,6 @@ static int vop_initial(struct vop *vop)
 	clk_disable(vop->aclk);
 
 	vop->is_enabled = false;
-	vop->vblank_active = false;
 
 	return 0;