diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 838726b..0aa72ac 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1222,6 +1222,14 @@ static int mmc_select_hs400(struct mmc_card *card)
 	mmc_set_timing(host, MMC_TIMING_MMC_HS400);
 	mmc_set_bus_speed(card);
 
+	if (host->ops->execute_hs400_tuning) {
+		mmc_retune_disable(host);
+		err = host->ops->execute_hs400_tuning(host, card);
+		mmc_retune_enable(host);
+		if (err)
+			goto out_err;
+	}
+
 	if (host->ops->hs400_complete)
 		host->ops->hs400_complete(host);
 
diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 4dfc246..484f5c3 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -258,6 +258,7 @@
 #define MSDC_PAD_TUNE_RD_SEL	  (0x1 << 13)   /* RW */
 #define MSDC_PAD_TUNE_CMD_SEL	  (0x1 << 21)   /* RW */
 
+#define PAD_DS_TUNE_DLY_SEL       (0x1 << 0)	/* RW */
 #define PAD_DS_TUNE_DLY1	  (0x1f << 2)   /* RW */
 #define PAD_DS_TUNE_DLY2	  (0x1f << 7)   /* RW */
 #define PAD_DS_TUNE_DLY3	  (0x1f << 12)  /* RW */
@@ -301,6 +302,11 @@
 #define PAD_CMD_RD_RXDLY_SEL    (0x1 << 11)     /* RW */
 #define PAD_CMD_TX_DLY          (0x1f << 12)    /* RW */
 
+/* EMMC50_PAD_DS_TUNE mask */
+#define PAD_DS_DLY_SEL		(0x1 << 16)	/* RW */
+#define PAD_DS_DLY1		(0x1f << 10)	/* RW */
+#define PAD_DS_DLY3		(0x1f << 0)	/* RW */
+
 #define REQ_CMD_EIO  (0x1 << 0)
 #define REQ_CMD_TMO  (0x1 << 1)
 #define REQ_DAT_ERR  (0x1 << 2)
@@ -448,11 +454,13 @@ struct msdc_host {
 	bool vqmmc_enabled;
 	u32 latch_ck;
 	u32 hs400_ds_delay;
+	u32 hs400_ds_dly3;
 	u32 hs200_cmd_int_delay; /* cmd internal delay for HS200/SDR104 */
 	u32 hs400_cmd_int_delay; /* cmd internal delay for HS400 */
 	bool hs400_cmd_resp_sel_rising;
 				 /* cmd response sample selection for HS400 */
 	bool hs400_mode;	/* current eMMC will run at hs400 mode */
+	bool hs400_tuning;	/* hs400 mode online tuning */
 	bool internal_cd;	/* Use internal card-detect logic */
 	bool cqhci;		/* support eMMC hw cmdq */
 	struct msdc_save_para save_para; /* used when gate HCLK */
@@ -1190,7 +1198,8 @@ static bool msdc_cmd_done(struct msdc_host *host, int events,
 	if (!sbc_error && !(events & MSDC_INT_CMDRDY)) {
 		if (events & MSDC_INT_CMDTMO ||
 		    (cmd->opcode != MMC_SEND_TUNING_BLOCK &&
-		     cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200))
+		     cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200 &&
+		     !host->hs400_tuning))
 			/*
 			 * should not clear fifo/interrupt as the tune data
 			 * may have alreay come when cmd19/cmd21 gets response
@@ -1287,7 +1296,8 @@ static void msdc_cmd_next(struct msdc_host *host,
 	if ((cmd->error &&
 	    !(cmd->error == -EILSEQ &&
 	      (cmd->opcode == MMC_SEND_TUNING_BLOCK ||
-	       cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200))) ||
+	       cmd->opcode == MMC_SEND_TUNING_BLOCK_HS200 ||
+	       host->hs400_tuning))) ||
 	    (mrq->sbc && mrq->sbc->error))
 		msdc_request_done(host, mrq);
 	else if (cmd == mrq->sbc)
@@ -2251,6 +2261,106 @@ static int msdc_prepare_hs400_tuning(struct mmc_host *mmc, struct mmc_ios *ios)
 	return 0;
 }
 
+static int msdc_send_cxd_data(struct mmc_card *card, struct mmc_host *host)
+{
+	struct mmc_request mrq = {};
+	struct mmc_command cmd = {};
+	struct mmc_data data = {};
+	unsigned int len = 512;
+	struct scatterlist sg;
+	u8 *ext_csd;
+
+	ext_csd = kzalloc(len, GFP_KERNEL);
+	if (!ext_csd)
+		return -ENOMEM;
+
+	mrq.cmd = &cmd;
+	mrq.data = &data;
+
+	cmd.opcode = MMC_SEND_EXT_CSD;
+	cmd.arg = 0;
+	cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
+
+	data.blksz = len;
+	data.blocks = 1;
+	data.flags = MMC_DATA_READ;
+	data.sg = &sg;
+	data.sg_len = 1;
+
+	sg_init_one(&sg, ext_csd, len);
+	mmc_set_data_timeout(&data, card);
+	mmc_wait_for_req(host, &mrq);
+
+	kfree(ext_csd);
+
+	if (cmd.error)
+		return cmd.error;
+	if (data.error)
+		return data.error;
+
+	return 0;
+}
+
+static int msdc_execute_hs400_tuning(struct mmc_host *mmc, struct mmc_card *card)
+{
+	struct msdc_host *host = mmc_priv(mmc);
+	struct msdc_delay_phase dly1_delay;
+	u32 val, result_dly1 = 0;
+	int i, ret;
+
+	if (host->top_base) {
+		sdr_set_bits(host->top_base + EMMC50_PAD_DS_TUNE,
+			     PAD_DS_DLY_SEL);
+		if (host->hs400_ds_dly3)
+			sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
+				      PAD_DS_DLY3, host->hs400_ds_dly3);
+	} else {
+		sdr_set_bits(host->base + PAD_DS_TUNE, PAD_DS_TUNE_DLY_SEL);
+		if (host->hs400_ds_dly3)
+			sdr_set_field(host->base + PAD_DS_TUNE,
+				      PAD_DS_TUNE_DLY3, host->hs400_ds_dly3);
+	}
+
+	host->hs400_tuning = true;
+	for (i = 0; i < PAD_DELAY_MAX; i++) {
+		if (host->top_base)
+			sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
+				      PAD_DS_DLY1, i);
+		else
+			sdr_set_field(host->base + PAD_DS_TUNE,
+				      PAD_DS_TUNE_DLY1, i);
+		ret = msdc_send_cxd_data(card, mmc);
+		if (!ret)
+			result_dly1 |= (1 << i);
+	}
+	host->hs400_tuning = false;
+
+	dly1_delay = get_best_delay(host, result_dly1);
+	if (dly1_delay.maxlen == 0) {
+		dev_err(host->dev, "Failed to get DLY1 delay!\n");
+		goto fail;
+	}
+	if (host->top_base)
+		sdr_set_field(host->top_base + EMMC50_PAD_DS_TUNE,
+			      PAD_DS_DLY1, dly1_delay.final_phase);
+	else
+		sdr_set_field(host->base + PAD_DS_TUNE,
+			      PAD_DS_TUNE_DLY1, dly1_delay.final_phase);
+
+	if (host->top_base)
+		val = readl(host->top_base + EMMC50_PAD_DS_TUNE);
+	else
+		val = readl(host->base + PAD_DS_TUNE);
+
+	dev_info(host->dev, "Fianl PAD_DS_TUNE: 0x%x\n", val);
+
+	return 0;
+
+fail:
+	dev_err(host->dev, "Failed to tuning DS pin delay!\n");
+	return -EIO;
+}
+
 static void msdc_hw_reset(struct mmc_host *mmc)
 {
 	struct msdc_host *host = mmc_priv(mmc);
@@ -2377,6 +2487,7 @@ static void msdc_cqe_post_disable(struct mmc_host *mmc)
 	.card_busy = msdc_card_busy,
 	.execute_tuning = msdc_execute_tuning,
 	.prepare_hs400_tuning = msdc_prepare_hs400_tuning,
+	.execute_hs400_tuning = msdc_execute_hs400_tuning,
 	.hw_reset = msdc_hw_reset,
 };
 
@@ -2396,6 +2507,9 @@ static void msdc_of_property_parse(struct platform_device *pdev,
 	of_property_read_u32(pdev->dev.of_node, "hs400-ds-delay",
 			     &host->hs400_ds_delay);
 
+	of_property_read_u32(pdev->dev.of_node, "mediatek,hs400-ds-dly3",
+			     &host->hs400_ds_dly3);
+
 	of_property_read_u32(pdev->dev.of_node, "mediatek,hs200-cmd-int-delay",
 			     &host->hs200_cmd_int_delay);
 
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index ff1a251..7552d5e 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -162,6 +162,9 @@ struct mmc_host_ops {
 	/* Prepare HS400 target operating frequency depending host driver */
 	int	(*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
 
+	/* Execute HS400 tuning depending host driver */
+	int	(*execute_hs400_tuning)(struct mmc_host *host, struct mmc_card *card);
+
 	/* Prepare switch to DDR during the HS400 init sequence */
 	int	(*hs400_prepare_ddr)(struct mmc_host *host);
 
