From: Paul SAGE <paul.sage@42.fr>

On some systems (e.g. iMac 20,1 with BCM57766), the tg3 driver reads
a default placeholder mac address (00:10:18:00:00:00) from the
mailbox. The correct value on those systems are stored in the
'local-mac-address' property.

This patch, detect the default value and tries to retrieve
the correct address from the device_get_mac_address
function instead.

The patch has been tested on two different systems:
- iMac 20,1 (BCM57766) model which use the local-mac-address property
- iMac 13,2 (BCM57766) model which can use the mailbox,
    NVRAM or MAC control registers

Tested-by: Rishon Jonathan R <mithicalaviator85@gmail.com>

Co-developed-by: Vincent MORVAN <vinc@42.fr>
Signed-off-by: Vincent MORVAN <vinc@42.fr>
Signed-off-by: Paul SAGE <paul.sage@42.fr>
Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>

---
---
v4:
- Used static for default_mac_address
- Returned the value of device_get_mac_address in tg3_get_device_address
v3:
- Used ether_addr_equal
v2:
- Wrapped commit message to 70 characters
- Removed BROADCOM_OUI constant
---
---
 drivers/net/ethernet/broadcom/tg3.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 75f66587983d..a80f27e66ab5 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -17030,6 +17030,13 @@ static int tg3_get_invariants(struct tg3 *tp, const struct pci_device_id *ent)
 	return err;
 }
 
+static int tg3_is_default_mac_address(u8 *addr)
+{
+	static const u8 default_mac_address[ETH_ALEN] = { 0x00, 0x10, 0x18, 0x00, 0x00, 0x00 };
+
+	return ether_addr_equal(default_mac_address, addr);
+}
+
 static int tg3_get_device_address(struct tg3 *tp, u8 *addr)
 {
 	u32 hi, lo, mac_offset;
@@ -17103,6 +17110,10 @@ static int tg3_get_device_address(struct tg3 *tp, u8 *addr)
 
 	if (!is_valid_ether_addr(addr))
 		return -EINVAL;
+
+	if (tg3_is_default_mac_address(addr))
+		return device_get_mac_address(&tp->pdev->dev, addr);
+
 	return 0;
 }
 
-- 
2.43.0

On Sat, Mar 14, 2026 at 2:54 PM Atharva Tiwari
<atharvatiwarilinuxdev@gmail.com> wrote:
>
> From: Paul SAGE <paul.sage@42.fr>
>
> On some systems (e.g. iMac 20,1 with BCM57766), the tg3 driver reads
> a default placeholder mac address (00:10:18:00:00:00) from the
> mailbox. The correct value on those systems are stored in the
> 'local-mac-address' property.
>
> This patch, detect the default value and tries to retrieve
> the correct address from the device_get_mac_address
> function instead.
>
> The patch has been tested on two different systems:
> - iMac 20,1 (BCM57766) model which use the local-mac-address property
> - iMac 13,2 (BCM57766) model which can use the mailbox,
>     NVRAM or MAC control registers
>
> Tested-by: Rishon Jonathan R <mithicalaviator85@gmail.com>
>
> Co-developed-by: Vincent MORVAN <vinc@42.fr>
> Signed-off-by: Vincent MORVAN <vinc@42.fr>
> Signed-off-by: Paul SAGE <paul.sage@42.fr>
> Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>

Reviewed-by: Michael Chan <michael.chan@broadcom.com>