[PATCH 1/4 v2] powerpc: document max-speed and interface-type properties

[Kim Phillips]

On Tue, 17 Apr 2007 01:18:56 +0200
Segher Boessenkool <segher at kernel.crashing.org> wrote:

> > I don't need to know what type the PHY is, e.g. whether it's m88e11x1
> > compatible or not, the phylib handles that.
> 
> You need to tell the phylib what kind of bus the PHY uses.

sure, and ucc_geth does just that based on the interface-type property,
in addition to correspondingly programming the UCC.

> You can put "rgmii" or whatever in the "compatible" property
> as well.
> 
I don't understand how intermixing PHY device compatibility with the
UCC connection to the PHY would be a good thing.

> > If I were to put the properties in the PHY node, I wouldn't be able to
> > describe a 1000Mbit/s capable UCC connected to a 100Mbit/s capable PHY,
> > or vice versa.
> 
> Of course you can.  The "compatible" in the enet node
> implies it can do 1000Mbps; the "compatible" in the
> PHY node implies it does 100Mbps.

compatible in the UCC node is currently set to "ucc_geth", which does
not necessarily imply that that UCC can do 1000Mbit/s.  Some UCCs can
only do 100Mbit/s.

We currently do not have hardware that connects UCC with max-speed x
with a PHY with max. speed capability of y, where x != y, so there is
currently no need to specify the speed of the PHY.  Not that that would
be needed; the phylib would call ucc_geth's adjust_link with the new
speed.  Note that the max-speed property is used to set registers in the
UCC only.

Kim