[U-Boot] smc911x runtime detection (was: TI: OMAP3: Overo Tobi ethernet support)

[Ben Warren]

Hi Olof,
On Sat, Sep 26, 2009 at 8:53 AM, Olof Johansson <olof at lixom.net> wrote:

>
> On Sep 26, 2009, at 1:13 AM, Dirk Behme wrote:
>
>  Olof Johansson wrote:
>>
>>> Add setup for ethernet on Tobi, allowing kernel/ramdisk to be loaded
>>> over tftp.
>>> Based on the omap3 evm code. I added a new highlevel define for Tobi
>>> to avoid having it dependent on CMD_NET (which would seem backward in
>>> this case).
>>>
>>
>> First: This is only a request for comment for possible future improvement.
>> It doesn't ask for any changes in this patch or is any nack. Now to the
>> content ;)
>>
>> It seems that Steve found a way for runtime detection of smc911x making
>> CONFIG_OMAP3_OVERO_TOBI more or less obsolete (from [1]) :
>>
>
> Looks like a good idea. I guess the risk is if there's ever another carrier
> board with something on the same chip select that happens to return
> something at that address, thus causing false detection. Is that a valid
> concern?
>
> It is a good idea in principle, but just reading and expecting *something*
is a fatal flaw.  I don't know about these ones in particular, but
memory-mapped chips often have ID registers that are RO and have
well-documented contents.  If somebody can find something like that here,
let's do it.

>
> -Olof
>
> regards,
Ben