net: ethernet: ti: am65-cpsw: fixup PHY mode for fixed RGMII TX delay

All am65-cpsw controllers have a fixed TX delay, so the PHY interface
mode must be fixed up to account for this.

Modes that claim to a delay on the PCB can't actually work. Warn people
to update their Device Trees if one of the unsupported modes is specified.

Signed-off-by: Matthias Schiffer <[email protected]>
Reviewed-by: Maxime Chevallier <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Reviewed-by: Siddharth Vadapalli <[email protected]>
Link: https://patch.msgid.link/9b3fb1fbf719bef30702192155c6413cd5de5dcf.1750756583.git.matthias.schiffer@ew.tq-group.com
Signed-off-by: Paolo Abeni <[email protected]>

Author: tq-schifferm

drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -2602,6 +2602,7 @@ static int am65_cpsw_nuss_init_slave_ports(struct am65_cpsw_common *common)
 		return -ENOENT;
 
 	for_each_child_of_node(node, port_np) {
+		phy_interface_t phy_if;
 		struct am65_cpsw_port *port;
 		u32 port_id;
 
@@ -2667,14 +2668,36 @@ static int am65_cpsw_nuss_init_slave_ports(struct am65_cpsw_common *common)
 
 		/* get phy/link info */
 		port->slave.port_np = of_node_get(port_np);
-		ret = of_get_phy_mode(port_np, &port->slave.phy_if);
+		ret = of_get_phy_mode(port_np, &phy_if);
 		if (ret) {
 			dev_err(dev, "%pOF read phy-mode err %d\n",
 				port_np, ret);
 			goto of_node_put;
 		}
 
-		ret = phy_set_mode_ext(port->slave.ifphy, PHY_MODE_ETHERNET, port->slave.phy_if);
+		/* CPSW controllers supported by this driver have a fixed
+		 * internal TX delay in RGMII mode. Fix up PHY mode to account
+		 * for this and warn about Device Trees that claim to have a TX
+		 * delay on the PCB.
+		 */
+		switch (phy_if) {
+		case PHY_INTERFACE_MODE_RGMII_ID:
+			phy_if = PHY_INTERFACE_MODE_RGMII_RXID;
+			break;
+		case PHY_INTERFACE_MODE_RGMII_TXID:
+			phy_if = PHY_INTERFACE_MODE_RGMII;
+			break;
+		case PHY_INTERFACE_MODE_RGMII:
+		case PHY_INTERFACE_MODE_RGMII_RXID:
+			dev_warn(dev,
+				 "RGMII mode without internal TX delay unsupported; please fix your Device Tree\n");
+			break;
+		default:
+			break;
+		}
+
+		port->slave.phy_if = phy_if;
+		ret = phy_set_mode_ext(port->slave.ifphy, PHY_MODE_ETHERNET, phy_if);
 		if (ret)
 			goto of_node_put;