net: stmmac: Limit the number of MTL queues to hardware capability

BugLink: https://bugs.launchpad.net/bugs/2103829

[ Upstream commit f5fb35a3d6b36d378b2e2ecbfb9caa337d5428e6 ]

The number of MTL queues to use is specified by the parameter
"snps,{tx,rx}-queues-to-use" from stmmac_platform layer.

However, the maximum numbers of queues are constrained by upper limits
determined by the capability of each hardware feature. It's appropriate
to limit the values not to exceed the upper limit values and display
a warning message.

This only works if the hardware capability has the upper limit values.

Fixes: d976a52 ("net: stmmac: multiple queues dt configuration")
Signed-off-by: Kunihiko Hayashi <[email protected]>
Reviewed-by: Yanteng Si <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Noah Wager <[email protected]>
Signed-off-by: Mehmet Basaran <[email protected]>

Author: khayash1

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

@@ -7274,6 +7274,21 @@ static int stmmac_hw_init(struct stmmac_priv *priv)
 	if (priv->dma_cap.tsoen)
 		dev_info(priv->device, "TSO supported\n");
 
+	if (priv->dma_cap.number_rx_queues &&
+	    priv->plat->rx_queues_to_use > priv->dma_cap.number_rx_queues) {
+		dev_warn(priv->device,
+			 "Number of Rx queues (%u) exceeds dma capability\n",
+			 priv->plat->rx_queues_to_use);
+		priv->plat->rx_queues_to_use = priv->dma_cap.number_rx_queues;
+	}
+	if (priv->dma_cap.number_tx_queues &&
+	    priv->plat->tx_queues_to_use > priv->dma_cap.number_tx_queues) {
+		dev_warn(priv->device,
+			 "Number of Tx queues (%u) exceeds dma capability\n",
+			 priv->plat->tx_queues_to_use);
+		priv->plat->tx_queues_to_use = priv->dma_cap.number_tx_queues;
+	}
+
 	priv->hw->vlan_fail_q_en =
 		(priv->plat->flags & STMMAC_FLAG_VLAN_FAIL_Q_EN);
 	priv->hw->vlan_fail_q = priv->plat->vlan_fail_q;