drm/mediatek: Detect CMDQ execution timeout

CMDQ is used to update display register in vblank period, so
it should be execute in next vblank. If it fail to execute
in next 2 vblank, tiemout happen.
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -55,6 +55,7 @@ struct mtk_drm_crtc {
 	struct mbox_client		cmdq_cl;
 	struct mbox_chan		*cmdq_chan;
 	u32				cmdq_event;
+	u32				cmdq_vblank_cnt;
 #endif
 
 	struct device			*mmsys_dev;
@@ -269,6 +270,7 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
 	struct mtk_drm_crtc *mtk_crtc = container_of(cl, struct mtk_drm_crtc, cmdq_cl);
 	struct cmdq_cb_data *data = mssg;
 
+	mtk_crtc->cmdq_vblank_cnt = 0;
 	mtk_drm_cmdq_pkt_destroy(mtk_crtc->cmdq_chan, data->pkt);
 }
 #endif
@@ -524,6 +526,11 @@ static void mtk_drm_crtc_update_config(struct mtk_drm_crtc *mtk_crtc,
 					    cmdq_handle->pa_base,
 					    cmdq_handle->cmd_buf_size,
 					    DMA_TO_DEVICE);
+		/*
+		 * CMDQ command should execute in next vblank,
+		 * If it fail to execute in next 2 vblank, timeout happen.
+		 */
+		mtk_crtc->cmdq_vblank_cnt = 2;
 		mbox_send_message(mtk_crtc->cmdq_chan, cmdq_handle);
 		mbox_client_txdone(mtk_crtc->cmdq_chan, 0);
 	}
@@ -540,11 +547,14 @@ static void mtk_crtc_ddp_irq(void *data)
 
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
 	if (!priv->data->shadow_register && !mtk_crtc->cmdq_chan)
+		mtk_crtc_ddp_config(crtc, NULL);
+	else if (mtk_crtc->cmdq_vblank_cnt > 0 && --mtk_crtc->cmdq_vblank_cnt == 0)
+		DRM_ERROR("mtk_crtc %d CMDQ execute command timeout!\n",
+			  drm_crtc_index(&mtk_crtc->base));
 #else
 	if (!priv->data->shadow_register)
-#endif
 		mtk_crtc_ddp_config(crtc, NULL);
-
+#endif
 	mtk_drm_finish_page_flip(mtk_crtc);
 }