[U-Boot] [PATCH v2] fdt: rework fdt_fixup_ethernet() to use env instead of bd_t

[Jerry Van Baren <gvb.uboot@gmail.com>]

Wolfgang Denk wrote:
> Dear Kumar Gala,
> 
> In message <119C6E28-E979-4B97-87AD-9603CD5FFDAA@kernel.crashing.org> you wrote:
>>>> This makes the code a bit more flexible to the number of ethernet
>>>> interfaces.  Right now we assume a max of 10 interfaces.
>>> Hm... where exactly is this artificial limit coming from? Do we really
>>> need it?
>> We need some upper limit to stop checking at.
> 
> The upper limit should be the real  (configured)  number  of  network
> interfaces, not some artificial limit which is either too high or too
> low.

It is (was) - CFG_MAX_NUM_ETH:
+		for (i = 0; i < CFG_MAX_NUM_ETH; i++) {

Actually, I don't see any arbitrary upper limit in the code, including 
Kumar's value of 10 (well, until you overflow the strings, anyway, but 
that is 100 interfaces).

>>> If we assume,  that  all  existing  interfaces  must  have  addresses
>>> assigned, we could use a "break" here instead of the "continue". That
>>> would be (1) much faster on most boards and (2) would allow us to get
>>> rid of the artifical limit of 10.

CFG_MAX_NUM_ETH would presumably be the physical max and the 
/aliases/ethernet (and associated env variables) should *not* be sparse, 
therefore I agree with the the "break" recommendation.

>>> What do you think?
>> I dont like making this assumption and do think its too much work to  
>> check 10 possible aliases and skip to the next one if it doesn't exist.
> 
> I do not want to see any  such  hard-coded  limits  if  they  can  be
> avoided. Which problem do you see to stop here at the first interface
> that has no MAC address assigned to it?

I originally wrote to support sparse ethernet MAC addresses, but on 
reflection I don't think that is an issue because we will have 
/aliases/ethernet[0-9]+ which won't be sparse, even if the actual SOC 
(e.g. PowerQuicc) channels that are used for ethernet are used in a 
sparse manner.

> Best regards,
> 
> Wolfgang Denk

Best regards,
gvb