diff --git a/drivers/i3c/i3c_npcm4xx.c b/drivers/i3c/i3c_npcm4xx.c
index 1d3a64e3aedddb..7cc52cc622d233 100644
--- a/drivers/i3c/i3c_npcm4xx.c
+++ b/drivers/i3c/i3c_npcm4xx.c
@@ -582,8 +582,8 @@ I3C_ErrCode_Enum hal_I3C_Config_Device(I3C_DEVICE_INFO_t *pDevice)
 		PDMA->SCATBA = (uint32_t) I3C_SCATTER_GATHER_TABLE.SCAT_DSCT;
 	}
 
-//	hal_I3C_set_MAXRD(port, pDevice->max_rd_len);
-//	hal_I3C_set_MAXWR(port, pDevice->max_wr_len);
+	hal_I3C_set_MAXRD(port, pDevice->max_rd_len);
+	hal_I3C_set_MAXWR(port, pDevice->max_wr_len);
 
 	/* Used for the Mixed bus to send the first START frame */
 	mconfig &= ~I3C_MCONFIG_ODHPP_MASK;
@@ -3430,7 +3430,10 @@ if (intmasked == 0) return;
 		 * 1. We must terminate previous RX DMA / FIFO before master send "Index" / Data
 		 * 2. We must init RX DMA to get "Index" and data
 		 */
-		I3C_Slave_Handle_DMA((uint32_t)pDevice);
+		if (intmasked & I3C_INTMASKED_STOP_MASK) {
+			/* update tx buffer here, only when slave doesn't get STOP */
+			I3C_Slave_Handle_DMA((uint32_t)pDevice);
+		}
 
 		I3C_SET_REG_STATUS(I3C_IF, I3C_STATUS_START_MASK);
 	}
@@ -3441,7 +3444,8 @@ if (intmasked == 0) return;
 	}
 
 	if (intmasked & I3C_INTMASKED_CCC_MASK) {
-		I3C_SET_REG_STATUS(I3C_IF, I3C_STATUS_CCC_MASK);
+		/* Can't reset here, will validate CCC in I3C_Slave_Handle_DMA() */
+		/* I3C_SET_REG_STATUS(I3C_IF, I3C_STATUS_CCC_MASK); */
 	}
 
 	if (intmasked & I3C_INTMASKED_DDRMATCHED_MASK) {
@@ -3645,9 +3649,9 @@ void I3C_Slave_Handle_DMA(__u32 Parm)
 			PDMA->CHCTL &= ~MaskBit(port + I3C_PORT_MAX);
 
 			if (I3C_GET_REG_STATUS(port) & I3C_STATUS_CCC_MASK) {
-				/* reserved for vendor CCC */
+				/* reserved for vendor CCC, drop rx data directly */
 				if (slvRxBuf[port][0] == CCC_BROADCAST_SETAASA) {
-
+					LOG_WRN("rcv setaasa...");
 				}
 
 				/* we can't support SETAASA because DYNADDR is RO. */
@@ -3938,7 +3942,7 @@ static void sir_allowed_worker(struct k_work *work)
 {
 	struct i3c_npcm4xx_obj *obj = CONTAINER_OF(work, struct i3c_npcm4xx_obj, work);
 
-	k_msleep(1000);
+	/* k_msleep(1000); */
 	obj->sir_allowed_by_sw = 1;
 }
 
@@ -3991,8 +3995,8 @@ static int i3c_npcm4xx_init(const struct device *dev)
 
 	pDevice->staticAddr = config->assigned_addr;
 
-	pDevice->max_rd_len = 1024; // I3C_PAYLOAD_SIZE_MAX;
-	pDevice->max_wr_len = 1024; // I3C_PAYLOAD_SIZE_MAX;
+	pDevice->max_rd_len = I3C_PAYLOAD_SIZE_MAX;
+	pDevice->max_wr_len = I3C_PAYLOAD_SIZE_MAX;
 
 	if (config->slave) {
 		if (config->secondary)
diff --git a/tests/boards/npcm400f_evb/boards/npcm400f_evb.overlay b/tests/boards/npcm400f_evb/boards/npcm400f_evb.overlay
index d5860cf5c792d9..9570a5f8a21ccc 100644
--- a/tests/boards/npcm400f_evb/boards/npcm400f_evb.overlay
+++ b/tests/boards/npcm400f_evb/boards/npcm400f_evb.overlay
@@ -53,7 +53,7 @@
 		reg = <0x21>;
 		msg-size = <256>;
 		num-of-msgs = <4>;
-		mandatory-data-byte = <0xB0>;
+		mandatory-data-byte = <0xAE>;
 		label = "I3C_1_SMQ";
 		status = "okay";
 	};
diff --git a/tests/boards/npcm400f_evb/src/i3c.c b/tests/boards/npcm400f_evb/src/i3c.c
index eaccf06deda281..08a53e200177e9 100644
--- a/tests/boards/npcm400f_evb/src/i3c.c
+++ b/tests/boards/npcm400f_evb/src/i3c.c
@@ -89,7 +89,7 @@ static void test_i3c_slave_task(void *arg1, void *arg2, void *arg3)
 		/* Test part 1: read and compare the data */
 
 		/* reset rx buffer */
-		/* memset(test_data_rx_slv, 0x00, sizeof(test_data_rx_slv)); */
+		memset(test_data_rx_slv, 0x00, sizeof(test_data_rx_slv));
 
 		while (1) {
 			ret = i3c_slave_mqueue_read(slave_mq, (uint8_t *)test_data_rx_slv, TEST_PRIV_XFER_SIZE);
@@ -108,6 +108,8 @@ static void test_i3c_slave_task(void *arg1, void *arg2, void *arg3)
 
 		/* Test part 2: send IBI to notify the master device to get the pending data */
 		/* prepare_test_data(test_data_tx_slv, TEST_IBI_PAYLOAD_SIZE); */
+
+		/* for debug only */
 		memcpy(test_data_tx_slv, test_data_rx_slv, TEST_IBI_PAYLOAD_SIZE);
 		ret = i3c_slave_mqueue_write(slave_mq, test_data_tx_slv, TEST_IBI_PAYLOAD_SIZE);
 		ast_zassert_equal(ret, 0, "failed to do slave mqueue write");
@@ -157,14 +159,12 @@ static void test_i3c_ci(int count)
 	/* try to enter i3c mode */
 	/* assign dynamic address with setdasa or entdaa, doesn't support setaasa in slave mode */
 	i3c_master_send_rstdaa(dev_master);
-	/* i3c_master_send_aasa(dev_master); */
+	i3c_master_send_aasa(dev_master); /* Compatibility test for JESD403 */
 	i3c_master_send_entdaa(slave);
 	slave->info.i2c_mode = 0;
 
 	/* must wait for a while, for slave finish sir_allowed_worker ? */
-	/* if skip the delay, the following getpid will be nacked */
-	/* and dma will capture enec mask data later */
-	k_sleep(K_MSEC(2000));
+	/* k_sleep(K_USEC(1)); */
 
 	/* try to collect more slave info if called setaasa in the former */
 	i3c_master_send_getpid(dev_master, slave->info.dynamic_addr, &slave->info.pid);
@@ -193,7 +193,8 @@ static void test_i3c_ci(int count)
 	for (i = 0; i < count; i++) {
 		/* prepare request message */
 		prepare_test_data(test_data_tx_mst, TEST_PRIV_XFER_SIZE);
-		test_data_tx_mst[0] = i; /* for debug only */
+		/* test_data_tx_mst[0] = i; */ /* for debug only */
+		/* k_usleep(100); */ /* debug only */
 
 		/* Requester send request message */
 		xfer[0].rnw = 0;
@@ -227,6 +228,7 @@ static void test_i3c_ci(int count)
 		k_yield();
 		ret = i3c_master_priv_xfer(slave, &xfer[0], 1);
 		ast_zassert_mem_equal(test_data_tx_slv, test_data_rx_mst, TEST_IBI_PAYLOAD_SIZE, "data mismatch");
+		/*k_usleep(100);*/ /* debug only */
 	}
 }