diff --git a/target/linux/mediatek/files-5.4/drivers/net/phy/mediatek-ge.c b/target/linux/mediatek/files-5.4/drivers/net/phy/mediatek-ge.c
index 6d9663c..a833c2a 100644
--- a/target/linux/mediatek/files-5.4/drivers/net/phy/mediatek-ge.c
+++ b/target/linux/mediatek/files-5.4/drivers/net/phy/mediatek-ge.c
@@ -548,6 +548,20 @@
 		}
 	}
 
+	/* Prevent overflow */
+	for (i = 0; i < 12; i++) {
+		if (buf[i>>2] + bias[i] > 63) {
+			buf[i>>2] = 63;
+			bias[i] = 0;
+		} else if (buf[i>>2] + bias[i] < 0) {
+			/* Bias caused by board design may change in the future.
+			 * So check negative cases, too.
+			 */
+			buf[i>>2] = 0;
+			bias[i] = 0;
+		}
+	}
+
 	phy_modify_mmd(phydev, MDIO_MMD_VEND1, MTK_PHY_TXVLD_DA_RG,
 		       MTK_PHY_DA_TX_I2MPB_A_GBE_MASK, (buf[0] + bias[0]) << 10);
 	phy_modify_mmd(phydev, MDIO_MMD_VEND1, MTK_PHY_TXVLD_DA_RG,
@@ -604,6 +618,7 @@
 			      phy_cal_pair_t txg_calen_x)
 {
 	int bias[4] = {0};
+	int i;
 	switch(phydev->drv->phy_id) {
 		case 0x03a29481:
 		{
@@ -616,6 +631,15 @@
 			break;
 	}
 
+	for (i = 0; i < 4; i++) {
+		if (buf[i>>2] + bias[i] > 63) {
+			buf[i>>2] = 63;
+			bias[i] = 0;
+		} else if (buf[i>>2] + bias[i] < 0) {
+			buf[i>>2] = 0;
+			bias[i] = 0;
+		}
+	}
 	switch(txg_calen_x) {
 		case PAIR_A:
 			phy_modify_mmd(phydev, MDIO_MMD_VEND1, MTK_PHY_RG_DEV1E_REG53D,