diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index d3f350c25b9b..2eb284576336 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -511,6 +511,14 @@ bool stmmac_eee_init(struct stmmac_priv *priv)
 	return true;
 }
 
+static inline u32 stmmac_cdc_adjust(struct stmmac_priv *priv)
+{
+	/* Correct the clk domain crossing(CDC) error */
+	if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate)
+		return (2 * NSEC_PER_SEC) / priv->plat->clk_ptp_rate;
+	return 0;
+}
+
 /* stmmac_get_tx_hwtstamp - get HW TX timestamps
  * @priv: driver private structure
  * @p : descriptor pointer
@@ -524,7 +532,6 @@ static void stmmac_get_tx_hwtstamp(struct stmmac_priv *priv,
 {
 	struct skb_shared_hwtstamps shhwtstamp;
 	bool found = false;
-	s64 adjust = 0;
 	u64 ns = 0;
 
 	if (!priv->hwts_tx_en)
@@ -543,12 +550,7 @@ static void stmmac_get_tx_hwtstamp(struct stmmac_priv *priv,
 	}
 
 	if (found) {
-		/* Correct the clk domain crossing(CDC) error */
-		if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate) {
-			adjust += -(2 * (NSEC_PER_SEC /
-					 priv->plat->clk_ptp_rate));
-			ns += adjust;
-		}
+		ns -= stmmac_cdc_adjust(priv);
 
 		memset(&shhwtstamp, 0, sizeof(struct skb_shared_hwtstamps));
 		shhwtstamp.hwtstamp = ns_to_ktime(ns);
@@ -573,7 +575,6 @@ static void stmmac_get_rx_hwtstamp(struct stmmac_priv *priv, struct dma_desc *p,
 {
 	struct skb_shared_hwtstamps *shhwtstamp = NULL;
 	struct dma_desc *desc = p;
-	u64 adjust = 0;
 	u64 ns = 0;
 
 	if (!priv->hwts_rx_en)
@@ -586,11 +587,7 @@ static void stmmac_get_rx_hwtstamp(struct stmmac_priv *priv, struct dma_desc *p,
 	if (stmmac_get_rx_timestamp_status(priv, p, np, priv->adv_ts)) {
 		stmmac_get_timestamp(priv, desc, priv->adv_ts, &ns);
 
-		/* Correct the clk domain crossing(CDC) error */
-		if (priv->plat->has_gmac4 && priv->plat->clk_ptp_rate) {
-			adjust += 2 * (NSEC_PER_SEC / priv->plat->clk_ptp_rate);
-			ns -= adjust;
-		}
+		ns -= stmmac_cdc_adjust(priv);
 
 		netdev_dbg(priv->dev, "get valid RX hw timestamp %llu\n", ns);
 		shhwtstamp = skb_hwtstamps(skb);