net: stmmac: First Queue must always be in DCB mode

According to DWMAC databook the first queue operating mode
must always be in DCB.

As MTL_QUEUE_DCB = 1, we need to always set the first queue
operating mode to DCB otherwise driver will think that queue
is in AVB mode (because MTL_QUEUE_AVB = 0).
Signed-off-by: Jose Abreu <joabreu@synopsys.com>
Cc: Joao Pinto <jpinto@synopsys.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -150,6 +150,13 @@ static void stmmac_mtl_setup(struct platform_device *pdev,
 	plat->rx_queues_to_use = 1;
 	plat->tx_queues_to_use = 1;
 
+	/* First Queue must always be in DCB mode. As MTL_QUEUE_DCB = 1 we need
+	 * to always set this, otherwise Queue will be classified as AVB
+	 * (because MTL_QUEUE_AVB = 0).
+	 */
+	plat->rx_queues_cfg[0].mode_to_use = MTL_QUEUE_DCB;
+	plat->tx_queues_cfg[0].mode_to_use = MTL_QUEUE_DCB;
+
 	rx_node = of_parse_phandle(pdev->dev.of_node, "snps,mtl-rx-config", 0);
 	if (!rx_node)
 		return;