[PATCH] rockchip: board: assign up to 3 static Ethernet MAC addresses

[Quentin Schulz]

Hi MichaIng,

On 6/7/25 7:11 PM, MichaIng wrote:
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> 
> Some SBCs with Rockchip SoC provide 3 Ethernet ports, like the
> FriendlyELEC NanoPi R5S and NanoPi R6S. U-Boot assigns already eth*addr
> variables to ethernet* device tree node aliases, but for Rockchip
> boards, it generates only ethaddr and eth1addr so far.
> 
> To allow the assignment of 3 static MAC addresses, with this change,
> eth2addr is generated with a logic similar to how eth1addr is generated
> already:
> - eth1addr is currently derived from ethaddr by inverting the last bit,
> which raises or decreases the last hex digit of the MAC address by one.
> - Hereby, the eth2addr is derived from the value assigned to eth1addr,
> by inverting the last 2 bits. Hence, differs from the first ethaddr by
> an inverted second last bit, which raises or decreases the last hex
> digit of the MAC address by two. This assures a valid MAC address
> assigned to eth2addr, which always differs from ethaddr and eth1addr.
> 
> The change has been successfully tested on the NanoPi R5S and NanoPi
> R6S: With ethernet[0-2] device tree aliases (correctly) defined, both
> boards get 3 static MAC addresses.
> 

What's the number when we'll decide this is too many? I have a board 
with 5 Ethernet ports for example :)

You could set the eth2addr in your board file if you wanted instead of 
setting it for everybody.

I don't know how far we want to go to avoid defining unused ethXaddr 
variables in the environment? We could use of_alias_get_highest_id for 
example and generate enough environment variables based on that info?

The change looks ok though, so:

Reviewed-by: Quentin Schulz <quentin.schulz at cherry.de>

Thanks!
Quentin