net: enetc: set MAC RX FIFO to recommended value

On LS1028A, the MAC RX FIFO defaults to the value 2, which is too high
and may lead to RX lock-up under traffic at a rate higher than 6 Gbps.
Set it to 1 instead, as recommended by the hardware design team and by
later versions of the ENETC block guide.
Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Reviewed-by: Jason Liu <jason.hui.liu@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/enetc/enetc_hw.h

@@ -234,6 +234,8 @@ enum enetc_bdr_type {TX, RX};
 #define ENETC_PM0_MAXFRM	0x8014
 #define ENETC_SET_TX_MTU(val)	((val) << 16)
 #define ENETC_SET_MAXFRM(val)	((val) & 0xffff)
+#define ENETC_PM0_RX_FIFO	0x801c
+#define ENETC_PM0_RX_FIFO_VAL	1
 
 #define ENETC_PM_IMDIO_BASE	0x8030
 

drivers/net/ethernet/freescale/enetc/enetc_pf.c

@@ -490,6 +490,12 @@ static void enetc_configure_port_mac(struct enetc_hw *hw)
 
 	enetc_port_wr(hw, ENETC_PM1_CMD_CFG, ENETC_PM0_CMD_PHY_TX_EN |
 		      ENETC_PM0_CMD_TXP	| ENETC_PM0_PROMISC);
+
+	/* On LS1028A, the MAC RX FIFO defaults to 2, which is too high
+	 * and may lead to RX lock-up under traffic. Set it to 1 instead,
+	 * as recommended by the hardware team.
+	 */
+	enetc_port_wr(hw, ENETC_PM0_RX_FIFO, ENETC_PM0_RX_FIFO_VAL);
 }
 
 static void enetc_mac_config(struct enetc_hw *hw, phy_interface_t phy_mode)