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

[Michael Schwingen]

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