[PATCH v2 1/3] net: eth-uclass: Introduce NET_PREFER_ROM_MAC_ADDR

[Detlev Casanova <detlev.casanova@collabora.com>]

On some boards, a MAC address is set based on the CPU ID or other
information. This is usually done in the misc_init_r() function.

This becomes a problem for net devices that are probed after the call to
misc_init_r(), for example, when the ethernet is on a PCI port, which
needs to be enumerated.

In this case, misc_init_r() will set the ethaddr variable, then, when
the ethernet device is probed, if it has a ROM address, u-boot will warn
about a MAC address mismatch and use the misc_init_r() address instead
of the one in ROM.

The operating system later will most likely use the ROM MAC address,
which can be confusing.

To avoid that, this commit introduces NET_PREFER_ROM_MAC_ADDR that can
be set for boards that have such an interface.

Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
---
 net/Kconfig      | 7 +++++++
 net/eth-uclass.c | 9 +++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/net/Kconfig b/net/Kconfig
index 5dff6336293..1797c2cea35 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -227,6 +227,13 @@ config SERVERIP
 	string "Value of the default 'serverip' value in the environment"
 	depends on USE_SERVERIP
 
+config NET_PREFER_ROM_MAC_ADDR
+	bool "Prefer using HW MAC address if environment address differs"
+	default n
+	help
+	  In case of a MAC address mismatch between the environment and the HW,
+	  prefer using the HW address.
+
 config PROT_TCP
 	bool "TCP stack"
 	help
diff --git a/net/eth-uclass.c b/net/eth-uclass.c
index 3d0ec91dfa4..682de3ec7bd 100644
--- a/net/eth-uclass.c
+++ b/net/eth-uclass.c
@@ -584,8 +584,13 @@ static int eth_post_probe(struct udevice *dev)
 			       env_enetaddr);
 		}
 
-		/* Override the ROM MAC address */
-		memcpy(pdata->enetaddr, env_enetaddr, ARP_HLEN);
+		if (!IS_ENABLED(CONFIG_NET_PREFER_ROM_MAC_ADDR)) {
+			/* Override the ROM MAC address */
+			printf("Using address in environment\n");
+			memcpy(pdata->enetaddr, env_enetaddr, ARP_HLEN);
+		} else {
+			printf("Using address in %s\n", source);
+		}
 	} else if (is_valid_ethaddr(pdata->enetaddr)) {
 		eth_env_set_enetaddr_by_index("eth", dev_seq(dev),
 					      pdata->enetaddr);
-- 
2.43.2