[U-Boot] PPC + NatSemi dp83640 phy?

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

Hi Nathan,

Nathan French wrote:
> Hi all,
> 
> I've been tasked with bringing up a new board next week for my company
> that is essentially a Kilauea with a National Semiconductor DP83640
> ethernet phy.  We have U-Boot working on our previous board rev which
> used the Marvell 88E1111 ethernet phy which U-Boot supports.
> 
> I'm new to ethernet devices.  I see that both the 88E1111 and the
> DP83xxx devices use MII.  Does this mean the DP83640 may just work as
> is?

Maybe.  My impression of and experience with the MII standard is that it 
has lots of room for different "standard" implementations as well as 
non-standard behavior.  Maybe things are better now.  Or not.

Theoretically, you should be able to drop in any PHY, use just the 
standardized registers and behavior, and have it work.  In practice, 
maybe, maybe not.  My (somewhat dated) experience is that I ended up 
twiddling with "implementation extension" registers to get the behavior 
I wanted.

If you look at the u-boot and linux PHY drivers, you will see a lot of 
manufacturer's names.  Not a good sign.  On the other hand, there is 
also a concept of a "generic" PHY.  If "generic" works, that is great.

BTW, it is helpful to enable the MII command so that you can poke around 
in your PHY's registers.

> Thanks,
> 
> Nathan French

Have fun,
gvb