drm/mediatek: Use mailbox rx_callback instead of cmdq_task_cb

rx_callback is a standard mailbox callback mechanism and could cover the
function of proprietary cmdq_task_cb, so use the standard one instead of
the proprietary one.
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/gpu/drm/mediatek/mtk_drm_crtc.c

@@ -4,6 +4,8 @@
  */
 
 #include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/mailbox_controller.h>
 #include <linux/pm_runtime.h>
 #include <linux/soc/mediatek/mtk-cmdq.h>
 #include <linux/soc/mediatek/mtk-mmsys.h>
@@ -222,9 +224,11 @@ struct mtk_ddp_comp *mtk_drm_ddp_comp_for_plane(struct drm_crtc *crtc,
 }
 
 #if IS_REACHABLE(CONFIG_MTK_CMDQ)
-static void ddp_cmdq_cb(struct cmdq_cb_data data)
+static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
 {
-	cmdq_pkt_destroy(data.data);
+	struct cmdq_cb_data *data = mssg;
+
+	cmdq_pkt_destroy(data->pkt);
 }
 #endif
 
@@ -475,7 +479,12 @@ static void mtk_drm_crtc_update_config(struct mtk_drm_crtc *mtk_crtc,
 		cmdq_pkt_wfe(cmdq_handle, mtk_crtc->cmdq_event, false);
 		mtk_crtc_ddp_config(crtc, cmdq_handle);
 		cmdq_pkt_finalize(cmdq_handle);
-		cmdq_pkt_flush_async(cmdq_handle, ddp_cmdq_cb, cmdq_handle);
+		dma_sync_single_for_device(mtk_crtc->cmdq_client->chan->mbox->dev,
+					    cmdq_handle->pa_base,
+					    cmdq_handle->cmd_buf_size,
+					    DMA_TO_DEVICE);
+		mbox_send_message(mtk_crtc->cmdq_client->chan, cmdq_handle);
+		mbox_client_txdone(mtk_crtc->cmdq_client->chan, 0);
 	}
 #endif
 	mtk_crtc->config_updating = false;
@@ -842,6 +851,7 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 	}
 
 	if (mtk_crtc->cmdq_client) {
+		mtk_crtc->cmdq_client->client.rx_callback = ddp_cmdq_cb;
 		ret = of_property_read_u32_index(priv->mutex_node,
 						 "mediatek,gce-events",
 						 drm_crtc_index(&mtk_crtc->base),