RE: [PATCH] board: dhelectronics: imx: Use second Ethernet MAC also from fuse

[Christoph Niedermaier <cniedermaier@dh-electronics.com>]

From: Marek Vasut <marex@nabladev.com>
Sent: Friday, March 20, 2026 7:22 PM
> On 3/20/26 11:29 AM, Christoph Niedermaier wrote:
> 
> [...]
> 
>> +++ b/board/dhelectronics/dh_imx8mp/imx8mp_dhcom_pdk2.c
>> @@ -50,7 +50,7 @@ static int dh_imx8_setup_ethaddr(struct eeprom_id_page *eip)
>>       if (dh_get_mac_is_enabled("ethernet0"))
>>               return 0;
>>
>> -     if (!dh_imx_get_mac_from_fuse(enetaddr))
>> +     if (!dh_imx_get_mac_from_fuse(0, enetaddr))
>>               goto out;
>>
>>       if (!dh_get_value_from_eeprom_buffer(DH_MAC0, enetaddr, sizeof(enetaddr), eip))
>> @@ -75,8 +75,8 @@ static int dh_imx8_setup_eth1addr(struct eeprom_id_page *eip)
>>       if (dh_get_mac_is_enabled("ethernet1"))
>>               return 0;
>>
>> -     if (!dh_imx_get_mac_from_fuse(enetaddr))
>> -             goto increment_out;
>> +     if (!dh_imx_get_mac_from_fuse(1, enetaddr))
>> +             goto out;
> 
> The ordering in this and next hunk seems bogus.
> 
> If read from the (new/second) fuse slot 1 fails, the code should attempt
> to use fuse slot 0 content incremented by 1, just like it did before ...
> 
> "
> if (!dh_imx_get_mac_from_fuse(1, enetaddr))
>    goto out;
> if (!dh_imx_get_mac_from_fuse(0, enetaddr))
>    goto increment_out;
> "
> 
>>       if (!dh_get_value_from_eeprom_buffer(DH_MAC1, enetaddr, sizeof(enetaddr), eip))
>>               goto out;
>> @@ -92,6 +92,13 @@ static int dh_imx8_setup_eth1addr(struct eeprom_id_page *eip)
>>       if (!dh_get_mac_from_eeprom(enetaddr, "eeprom0"))
>>               goto increment_out;
>>
>> +     /*
>> +      * If only the first MAC address is fused but not the second, use the
>> +      * fused MAC address incremented by one, for the second MAC address.
>> +      */
>> +     if (!dh_imx_get_mac_from_fuse(0, enetaddr))
>> +             goto increment_out;
> ... this part would then be unnecessary.

That's how it's supposed to be. The two MAC addresses should be assigned the same
priority order and be as independent of each other as possible to avoid confusion.
Sources associated with the second MAC address therefore have a higher priority
than those associated with the first MAC address in the fuses. Using the fuse of
the first MAC address incremented by one as a fallback is the last resort if no
address is found for the second MAC address after the priority order has been
checked.


Regards
Christoph