diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
index 9caf79ba5ef1..4d5fb4b51cc4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c
@@ -719,8 +719,11 @@ static u32 stmmac_usec2riwt(u32 usec, struct stmmac_priv *priv)
 {
 	unsigned long clk = clk_get_rate(priv->plat->stmmac_clk);
 
-	if (!clk)
-		return 0;
+	if (!clk) {
+		clk = priv->plat->clk_ref_rate;
+		if (!clk)
+			return 0;
+	}
 
 	return (usec * (clk / 1000000)) / 256;
 }
@@ -729,8 +732,11 @@ static u32 stmmac_riwt2usec(u32 riwt, struct stmmac_priv *priv)
 {
 	unsigned long clk = clk_get_rate(priv->plat->stmmac_clk);
 
-	if (!clk)
-		return 0;
+	if (!clk) {
+		clk = priv->plat->clk_ref_rate;
+		if (!clk)
+			return 0;
+	}
 
 	return (riwt * 256) / (clk / 1000000);
 }
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 7ddfc65586b0..4335bd771ce5 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -184,6 +184,7 @@ struct plat_stmmacenet_data {
 	struct clk *pclk;
 	struct clk *clk_ptp_ref;
 	unsigned int clk_ptp_rate;
+	unsigned int clk_ref_rate;
 	struct reset_control *stmmac_rst;
 	struct stmmac_axi *axi;
 	int has_gmac4;