[U-Boot-Users] MPC8439E + Marvell 888E1111 (blah!)

[David Hawkins <dwh@ovro.caltech.edu>]

Hi Andy,

>> To minimize my porting effort for both U-Boot and
>> Linux, I decided to copy the MPC8349E-MDS-PB reference
>> design and use the Marvell 888E1111 gigabit transceiver
>> for the network interface.
> 
> You might want to look at the ITX design.  It's simpler.  The MDS/PB
> design is fairly modular, and might be more complicated than what you
> want.  But obviously, you would be the best judge of what you want
> your board to do.
>>
>> I find that the Marvell chipset documents are proprietary
>> and require the signing of an NDA to access.
> 
> Yeah, that seems to be a trend for PHY manufacturers.

After looking for alternatives, I started to get that feeling.

> Don't read this as an endorsement (I've not used it before), but
> http://www.national.com/pf/DP/DP83865.html is supported in u-boot, and
> looks like you can get the documentation with no restrictions (I
> downloaded the docs just a second ago).

Great! I can learn a little more about these types of parts.

> Also, you don't need to worry too much about which PHY you use from a
> software standpoint.  Many PHYs follow the 802.11 spec, and both
> u-boot and Linux have generic drivers which are used by default for
> unknown PHYs.  I frequently forget to enable my PHY driver in my
> kernel builds, and almost never have a problem.

Ok, good to know. I'd figured that was probably the case from
just general reading of PHY related questions/answers on the list.

> So you might just need to find a PHY, and make sure it doesn't require
> any special initialization or configuration.  Most PHYs should fall
> into that category.
> 
> And even if it does, the tsec/gianfar drivers for the ethernet on the
> 83xx have good (I think) infrastructure for using different PHYs, and
> the average PHY driver requires very little in the way of code.

Thanks! Just the sort of useful feedback I wanted :)

Its always a bit of a tradeoff; copying the design of a known-good
system (i.e., one that can be compared to when things don't work on
your new board!), and component features.

For example, the size of Marvell part on the MDS reference board
(BGA package) is 10mmx14mm, whereas the National part in a PQFP
package is 17x23mm. The Marvell part can take a 125MHz clock, but
the National can only use 25MHz. It turns out that I have use
for 125MHz elsewhere on my board ...

Out of interest, how does signing an NDA to get a data sheet
affect one's ability to write open-source software for the part?
For example, I'll need to sign an NDA to get the electrical and
mechanical characteristics of the Marvell part ... but then
I'd be hard-pressed not to look at the software features of
the device wouldn't I :) . Of course, the fact that the driver
already exists for this part means that the dilemma has already
been faced by someone else.

I guess I'll look at the terms of the NDA and see if it says
anything in there.

Ah well, back to my schematics then :)

Thanks,
Dave