net: lwip: move eth_init() out of new_netif()

Move the initialization of the ethernet devices out of the new_netif()
function. Indeed, new_netif() accepts a struct device argument, which
is expected to be valid and active. The activation and selection of
this device are achieved by eth_init() (on first time the network
stack is used) and eth_set_current(). This is what takes care of the
ethrotate and ethact environment variables. Therefore, move these calls
to a new function: net_lwip_set_current(), and use it whenever a
net-lwip command is run.

This patch hopefully fixes the incorrect net-lwip behavior observed on
boards with multiple ethernet interfaces [1].

Tested on an i.MX8MPlus EVK equipped wih two ethernet ports. The dhcp
command succeeds whether the cable is plugged into the first or second
port.

[1] https://lists.denx.de/pipermail/u-boot/2025-January/576326.html

Reported-by: E Shattow <e@freeshell.de>
Tested-by: E Shattow <e@freeshell.de>
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>

include/net-lwip.h

@@ -10,6 +10,7 @@ enum proto_t {
 	TFTPGET
 };
 
+void net_lwip_set_current(void);
 struct netif *net_lwip_new_netif(struct udevice *udev);
 struct netif *net_lwip_new_netif_noip(struct udevice *udev);
 void net_lwip_remove_netif(struct netif *netif);

net/lwip/dhcp.c

@@ -115,7 +115,7 @@ int do_dhcp(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 	int ret;
 	struct udevice *dev;
 
-	eth_set_current();
+	net_lwip_set_current();
 
 	dev = eth_get_dev();
 	if (!dev) {

net/lwip/dns.c

@@ -121,7 +121,7 @@ int do_dns(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 	if (argc == 3)
 		var = argv[2];
 
-	eth_set_current();
+	net_lwip_set_current();
 
 	return dns_loop(eth_get_dev(), name, var);
 }

net/lwip/net-lwip.c

@@ -127,6 +127,20 @@ static int get_udev_ipv4_info(struct udevice *dev, ip4_addr_t *ip,
 	return 0;
 }
 
+/* Initialize the lwIP stack and the ethernet devices and set current device  */
+void net_lwip_set_current(void)
+{
+	static bool init_done;
+
+	if (!init_done) {
+		eth_init_rings();
+		eth_init();
+		lwip_init();
+		init_done = true;
+	}
+	eth_set_current();
+}
+
 static struct netif *new_netif(struct udevice *udev, bool with_ip)
 {
 	unsigned char enetaddr[ARP_HLEN];
@@ -134,19 +148,10 @@ static struct netif *new_netif(struct udevice *udev, bool with_ip)
 	ip4_addr_t ip, mask, gw;
 	struct netif *netif;
 	int ret = 0;
-	static bool first_call = true;
 
 	if (!udev)
 		return NULL;
 
-	if (first_call) {
-		eth_init_rings();
-		/* Pick a valid active device, if any */
-		eth_init();
-		lwip_init();
-		first_call = false;
-	}
-
 	if (eth_start_udev(udev) < 0) {
 		log_err("Could not start %s\n", udev->name);
 		return NULL;

net/lwip/ping.c

@@ -168,7 +168,7 @@ int do_ping(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 	if (!ipaddr_aton(argv[1], &addr))
 		return CMD_RET_USAGE;
 
-	eth_set_current();
+	net_lwip_set_current();
 
 	if (ping_loop(eth_get_dev(), &addr) < 0)
 		return CMD_RET_FAILURE;

net/lwip/tftp.c

@@ -280,7 +280,7 @@ int do_tftpb(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 		goto out;
 	}
 
-	eth_set_current();
+	net_lwip_set_current();
 
 	if (tftp_loop(eth_get_dev(), laddr, fname, srvip, port) < 0)
 		ret = CMD_RET_FAILURE;

net/lwip/wget.c

@@ -354,7 +354,7 @@ static int wget_loop(struct udevice *udev, ulong dst_addr, char *uri)
 
 int wget_do_request(ulong dst_addr, char *uri)
 {
-	eth_set_current();
+	net_lwip_set_current();
 
 	if (!wget_info)
 		wget_info = &default_wget_info;