--- a/drivers/net/ethernet/mediatek/mtk_sgmii.c
+++ b/drivers/net/ethernet/mediatek/mtk_sgmii.c
-@@ -80,7 +80,8 @@ static int mtk_pcs_setup_mode_force(stru
+@@ -67,7 +67,8 @@ static int mtk_pcs_setup_mode_force(stru
val &= ~SGMII_AN_ENABLE;
regmap_write(mpcs->regmap, SGMSYS_PCS_CONTROL_1, val);
+ /* Set the speed etc but leave the duplex unchanged.
+ * The SGMII mode for 2.5gbit is the same as for 1gbit, expect the speed in ANA_RGC3 */
regmap_read(mpcs->regmap, SGMSYS_SGMII_MODE, &val);
- val &= SGMII_DUPLEX_FULL | ~SGMII_IF_MODE_MASK;
+ val &= SGMII_DUPLEX_HALF | ~SGMII_IF_MODE_MASK;
val |= SGMII_SPEED_1000;