diff --git a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
index b94f242420fc..0c84f5f7a82c 100644
--- a/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
+++ b/drivers/phy/freescale/phy-fsl-imx8mq-usb.c
@@ -502,6 +502,7 @@ static void imx8m_phy_tune(struct imx8mq_usb_phy *imx_phy)
 
 	if (imx_phy->pcs_tx_swing_full != PHY_TUNE_DEFAULT) {
 		value = readl(imx_phy->base + PHY_CTRL5);
+		value &= ~PHY_CTRL5_PCS_TX_SWING_FULL_MASK;
 		value |= FIELD_PREP(PHY_CTRL5_PCS_TX_SWING_FULL_MASK,
 				   imx_phy->pcs_tx_swing_full);
 		writel(value, imx_phy->base + PHY_CTRL5);