net: stmmac: Specify hardware capability value when FIFO size isn't specified

When Tx/Rx FIFO size is not specified in advance, the driver checks if
the value is zero and sets the hardware capability value in functions
where that value is used.

Consolidate the check and settings into function stmmac_hw_init() and
remove redundant other statements.

If FIFO size is zero and the hardware capability also doesn't have upper
limit values, return with an error message.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Reviewed-by: Yanteng Si <si.yanteng@linux.dev>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: khayash1

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

@@ -2424,11 +2424,6 @@ static void stmmac_dma_operation_mode(struct stmmac_priv *priv)
 	u32 chan = 0;
 	u8 qmode = 0;
 
-	if (rxfifosz == 0)
-		rxfifosz = priv->dma_cap.rx_fifo_size;
-	if (txfifosz == 0)
-		txfifosz = priv->dma_cap.tx_fifo_size;
-
 	/* Split up the shared Tx/Rx FIFO memory on DW QoS Eth and DW XGMAC */
 	if (priv->plat->has_gmac4 || priv->plat->has_xgmac) {
 		rxfifosz /= rx_channels_count;
@@ -2897,11 +2892,6 @@ static void stmmac_set_dma_operation_mode(struct stmmac_priv *priv, u32 txmode,
 	int rxfifosz = priv->plat->rx_fifo_size;
 	int txfifosz = priv->plat->tx_fifo_size;
 
-	if (rxfifosz == 0)
-		rxfifosz = priv->dma_cap.rx_fifo_size;
-	if (txfifosz == 0)
-		txfifosz = priv->dma_cap.tx_fifo_size;
-
 	/* Adjust for real per queue fifo size */
 	rxfifosz /= rx_channels_count;
 	txfifosz /= tx_channels_count;
@@ -5878,9 +5868,6 @@ static int stmmac_change_mtu(struct net_device *dev, int new_mtu)
 	const int mtu = new_mtu;
 	int ret;
 
-	if (txfifosz == 0)
-		txfifosz = priv->dma_cap.tx_fifo_size;
-
 	txfifosz /= priv->plat->tx_queues_to_use;
 
 	if (stmmac_xdp_is_enabled(priv) && new_mtu > ETH_DATA_LEN) {
@@ -7236,15 +7223,29 @@ static int stmmac_hw_init(struct stmmac_priv *priv)
 		priv->plat->tx_queues_to_use = priv->dma_cap.number_tx_queues;
 	}
 
-	if (priv->dma_cap.rx_fifo_size &&
-	    priv->plat->rx_fifo_size > priv->dma_cap.rx_fifo_size) {
+	if (!priv->plat->rx_fifo_size) {
+		if (priv->dma_cap.rx_fifo_size) {
+			priv->plat->rx_fifo_size = priv->dma_cap.rx_fifo_size;
+		} else {
+			dev_err(priv->device, "Can't specify Rx FIFO size\n");
+			return -ENODEV;
+		}
+	} else if (priv->dma_cap.rx_fifo_size &&
+		   priv->plat->rx_fifo_size > priv->dma_cap.rx_fifo_size) {
 		dev_warn(priv->device,
 			 "Rx FIFO size (%u) exceeds dma capability\n",
 			 priv->plat->rx_fifo_size);
 		priv->plat->rx_fifo_size = priv->dma_cap.rx_fifo_size;
 	}
-	if (priv->dma_cap.tx_fifo_size &&
-	    priv->plat->tx_fifo_size > priv->dma_cap.tx_fifo_size) {
+	if (!priv->plat->tx_fifo_size) {
+		if (priv->dma_cap.tx_fifo_size) {
+			priv->plat->tx_fifo_size = priv->dma_cap.tx_fifo_size;
+		} else {
+			dev_err(priv->device, "Can't specify Tx FIFO size\n");
+			return -ENODEV;
+		}
+	} else if (priv->dma_cap.tx_fifo_size &&
+		   priv->plat->tx_fifo_size > priv->dma_cap.tx_fifo_size) {
 		dev_warn(priv->device,
 			 "Tx FIFO size (%u) exceeds dma capability\n",
 			 priv->plat->tx_fifo_size);