net: systemport: wait for packet in umac_enable_set()

When umac_enable_set() is used to disable the UniMAC receiver or
transmitter, we need to make sure that we wait for a full-sized packet
to be processed because the UniMAC hardware stops on a packet boundary,
not immediately.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -1244,6 +1244,12 @@ static inline void umac_enable_set(struct bcm_sysport_priv *priv,
 	else
 		reg &= ~(CMD_RX_EN | CMD_TX_EN);
 	umac_writel(priv, reg, UMAC_CMD);
+
+	/* UniMAC stops on a packet boundary, wait for a full-sized packet
+	 * to be processed (1 msec).
+	 */
+	if (enable == 0)
+		usleep_range(1000, 2000);
 }
 
 static inline int umac_reset(struct bcm_sysport_priv *priv)