[PATCH RFC net-next 18/19] net: mvpp2: add ring size validation before enabling FC

[stefanc]

From: Stefan Chulski <stefanc@xxxxxxxxxxx>

This patch add ring size validation before enabling FC.
1. Flow control cannot be enabled if ring size is below start
threshold.
2. Flow control disabled if ring size set below start
threshold.

Signed-off-by: Stefan Chulski <stefanc@xxxxxxxxxxx>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index 06e1000..3607382 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -5372,6 +5372,15 @@ static int mvpp2_ethtool_set_ringparam(struct net_device *dev,
 	if (err)
 		return err;
 
+	if (ring->rx_pending < MSS_THRESHOLD_START && port->tx_fc) {
+		netdev_warn(dev, "TX FC disabled. Ring size is less than %d\n",
+			    MSS_THRESHOLD_START);
+		port->tx_fc = false;
+		mvpp2_rxq_disable_fc(port);
+		if (port->priv->hw_version == MVPP23)
+			mvpp23_rx_fifo_fc_en(port->priv, port->id, false);
+	}
+
 	if (!netif_running(dev)) {
 		port->rx_ring_size = ring->rx_pending;
 		port->tx_ring_size = ring->tx_pending;
@@ -5439,6 +5448,13 @@ static int mvpp2_ethtool_set_pause_param(struct net_device *dev,
 
 	if (pause->tx_pause && port->priv->global_tx_fc &&
 	    bm_underrun_protect) {
+		if (port->rx_ring_size < MSS_THRESHOLD_START) {
+			netdev_err(dev, "TX FC cannot be supported.");
+			netdev_err(dev, "Ring size is less than %d\n",
+				   MSS_THRESHOLD_START);
+			return -EINVAL;
+		}
+
 		port->tx_fc = true;
 		mvpp2_rxq_enable_fc(port);
 		if (port->priv->percpu_pools) {
-- 
1.9.1