net: stmmac: ethtool: Let user configure TX coalesce without RIWT

When RX Watchdog is disabled its currently not possible to configure TX
coalesce settings. Let user configure it anyway.
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_ethtool.c

@@ -746,8 +746,15 @@ static int stmmac_set_coalesce(struct net_device *dev,
 	    (ec->tx_max_coalesced_frames_high) || (ec->rate_sample_interval))
 		return -EOPNOTSUPP;
 
-	if (ec->rx_coalesce_usecs == 0)
-		return -EINVAL;
+	if (priv->use_riwt && (ec->rx_coalesce_usecs > 0)) {
+		rx_riwt = stmmac_usec2riwt(ec->rx_coalesce_usecs, priv);
+
+		if ((rx_riwt > MAX_DMA_RIWT) || (rx_riwt < MIN_DMA_RIWT))
+			return -EINVAL;
+
+		priv->rx_riwt = rx_riwt;
+		stmmac_rx_watchdog(priv, priv->ioaddr, priv->rx_riwt, rx_cnt);
+	}
 
 	if ((ec->tx_coalesce_usecs == 0) &&
 	    (ec->tx_max_coalesced_frames == 0))
@@ -757,20 +764,10 @@ static int stmmac_set_coalesce(struct net_device *dev,
 	    (ec->tx_max_coalesced_frames > STMMAC_TX_MAX_FRAMES))
 		return -EINVAL;
 
-	rx_riwt = stmmac_usec2riwt(ec->rx_coalesce_usecs, priv);
-
-	if ((rx_riwt > MAX_DMA_RIWT) || (rx_riwt < MIN_DMA_RIWT))
-		return -EINVAL;
-	else if (!priv->use_riwt)
-		return -EOPNOTSUPP;
-
 	/* Only copy relevant parameters, ignore all others. */
 	priv->tx_coal_frames = ec->tx_max_coalesced_frames;
 	priv->tx_coal_timer = ec->tx_coalesce_usecs;
 	priv->rx_coal_frames = ec->rx_max_coalesced_frames;
-	priv->rx_riwt = rx_riwt;
-	stmmac_rx_watchdog(priv, priv->ioaddr, priv->rx_riwt, rx_cnt);
-
 	return 0;
 }