diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
index 3bba2bea3a88..8f241b57fcf6 100644
--- a/drivers/net/phy/dp83640.c
+++ b/drivers/net/phy/dp83640.c
@@ -475,6 +475,13 @@ static int ptp_dp83640_enable(struct ptp_clock_info *ptp,
 					PTP_FALLING_EDGE |
 					PTP_STRICT_FLAGS))
 			return -EOPNOTSUPP;
+
+		/* Reject requests to enable time stamping on both edges. */
+		if ((rq->extts.flags & PTP_STRICT_FLAGS) &&
+		    (rq->extts.flags & PTP_ENABLE_FEATURE) &&
+		    (rq->extts.flags & PTP_EXTTS_EDGES) == PTP_EXTTS_EDGES)
+			return -EOPNOTSUPP;
+
 		index = rq->extts.index;
 		if (index >= N_EXT_TS)
 			return -EINVAL;