[U-Boot-Users] PATCH: add support for MII-connected ethernet switch for IPX42x

Michael Schwingen
2007-12-08T22:22:11Z

Jean-Christophe PLAGNIOL-VILLARD wrote:
> If you have a switch between your phy and your cpu the speed and
> the duplex must be specified by the phy driver.
>
Which PHY driver? The NPE code directly calls miiphy_read to acces
standard PHY registers, so where does a PHY driver come into play here?

> The best way is to add a function that request the phy status
> and do not wait the phy autonegociation like done in the kernel
> by read_status callback and it's implementation
> genphy_read_status.
>
I do not really see how that should work, for multiple reasons:
- speed/duplex on the MII bus depend on the attached switch and may be
different from the speed/duplex on any of the PHYs that are attached to
the switch.
- most switches (Marvell 88E6060 or similar) have multiple downstream
ports with PHYs - which one should I poll to get useful information?
Simply waiting for a link on any port will not guarantee that this is
the port via which the server is connected, so polling anything is
pretty useless IMHO.
- there are switches (Marvell 88E6050) that have no MDIO interface -
they have a fixed MII speed/duplex, and the CPU has no way to know about
the status of any of the PHYs.

I am a bit confused - could you please clarify in what direction the
code should evolve to solve these problems better than my patch does?

cu
Michael