drm/mediatek: Add wait_for_event for crtc disable by cmdq

mtk_drm_crtc_atomic_disable will send an async cmd to cmdq driver,
so it may not finish when cmdq_suspend is called sometimes.

Add wait_for_event after sending async disable plane cmd to make
sure the lastest cmd is done before cmdq_suspend.
Signed-off-by: jason-jh.lin <jason-jh.lin@mediatek.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20211202064039.20797-2-jason-jh.lin@mediatek.com/

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -56,6 +56,7 @@ struct mtk_drm_crtc {
 	struct cmdq_pkt			cmdq_handle;
 	u32				cmdq_event;
 	u32				cmdq_vblank_cnt;
+	wait_queue_head_t		cb_blocking_queue;
 #endif
 
 	struct device			*mmsys_dev;
@@ -314,6 +315,7 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
 	}
 
 	mtk_crtc->cmdq_vblank_cnt = 0;
+	wake_up(&mtk_crtc->cb_blocking_queue);
 }
 #endif
 
@@ -700,6 +702,13 @@ static void mtk_drm_crtc_atomic_disable(struct drm_crtc *crtc,
 	mtk_crtc->pending_planes = true;
 
 	mtk_drm_crtc_update_config(mtk_crtc, false);
+#if IS_REACHABLE(CONFIG_MTK_CMDQ)
+	/* Wait for planes to be disabled by cmdq */
+	if (mtk_crtc->cmdq_client.chan)
+		wait_event_timeout(mtk_crtc->cb_blocking_queue,
+				   mtk_crtc->cmdq_vblank_cnt == 0,
+				   msecs_to_jiffies(500));
+#endif
 	/* Wait for planes to be disabled */
 	drm_crtc_wait_one_vblank(crtc);
 
@@ -976,6 +985,9 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 				mtk_crtc->cmdq_client.chan = NULL;
 			}
 		}
+
+		/* for sending blocking cmd in crtc disable */
+		init_waitqueue_head(&mtk_crtc->cb_blocking_queue);
 	}
 #endif
 	return 0;