ftgmac100: Disable HW checksum generation on AST2400, enable on others

We found out that HW checksum generation only works from AST2500
onward. This disables it on AST2400 and removes the "no-hw-checksum"
properties in the device-trees. The problem we had wasn't related
to NC-SI.

Also rework the logic testing for that property so it can be used
to disable HW checksum generation and checking regardless of whether
NC-SI is used or not in case other variants out there need this.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/arm/boot/dts/aspeed-g4.dtsi

@@ -45,7 +45,6 @@ mac0: ethernet@1e660000 {
 			compatible = "aspeed,ast2400-mac", "faraday,ftgmac100";
 			reg = <0x1e660000 0x180>;
 			interrupts = <2>;
-			no-hw-checksum;
 			status = "disabled";
 		};
 
@@ -53,7 +52,6 @@ mac1: ethernet@1e680000 {
 			compatible = "aspeed,ast2400-mac", "faraday,ftgmac100";
 			reg = <0x1e680000 0x180>;
 			interrupts = <3>;
-			no-hw-checksum;
 			status = "disabled";
 		};
 

arch/arm/boot/dts/aspeed-g5.dtsi

@@ -36,7 +36,6 @@ mac0: ethernet@1e660000 {
 			compatible = "aspeed,ast2500-mac", "faraday,ftgmac100";
 			reg = <0x1e660000 0x180>;
 			interrupts = <2>;
-			no-hw-checksum;
 			status = "disabled";
 		};
 
@@ -44,7 +43,6 @@ mac1: ethernet@1e680000 {
 			compatible = "aspeed,ast2500-mac", "faraday,ftgmac100";
 			reg = <0x1e680000 0x180>;
 			interrupts = <3>;
-			no-hw-checksum;
 			status = "disabled";
 		};
 

drivers/net/ethernet/faraday/ftgmac100.c

@@ -1473,15 +1473,15 @@ static int ftgmac100_probe(struct platform_device *pdev)
 			goto err_setup_mdio;
 	}
 
-	/* We have to disable on-chip IP checksum functionality
-	 * when NCSI is enabled on the interface. It doesn't work
-	 * in that case.
-	 */
+	/* Base feature set */
 	netdev->features = NETIF_F_RXCSUM | NETIF_F_HW_CSUM |
 		NETIF_F_GRO | NETIF_F_SG;
-	if (priv->use_ncsi &&
-	    of_get_property(np, "no-hw-checksum", NULL))
+
+	/* AST2400  doesn't have working HW checksum generation */
+	if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac")))
 		netdev->features &= ~NETIF_F_HW_CSUM;
+	if (np && of_get_property(np, "no-hw-checksum", NULL))
+		netdev->features &= ~(NETIF_F_HW_CSUM | NETIF_F_RXCSUM);
 
 	/* register network device */
 	err = register_netdev(netdev);