RE: [EXT] Re: [V2 net-next] net: mvpp2: Add reserved port private flag configuration

quoted

2. CM3 code has very small footprint requirement, we cannot 
implement the complete Serdes and PHY infrastructure that kernel 
provides as part of CM3 application. Therefore I would like to 
continue relying on kernel configuration for that.

How can that work? How does Linux know when CM3 has up'ed the 
interface?

CM3 won't use this interface till ethtool priv flag was set, it can be done by communication over CM3 SRAM memory.

How does CM3 know the status of the link?

CM3 has access to MAC registers and can read port status bit.

How does CM3 set its
flow control depending on what auto-neg determines, etc?

Same as PPv2 Packet Processor RX and TX flow don't really care about auto-neg, flow control, etc.
CM3 can ignore it, all this stuff handled in MAC layer. CM3 just polling RX descriptor ring and using TX ring for transmit. 

quoted

3. In some cases we need to dynamically switch the port "user"
between CM3 and kernel. So I would like to preserve this 
functionality.

And how do you synchronize between Linux and CM3 so you know how is 
using it and who cannot use it?

      Andrew

I can add CM3 SRAM update into ethtool priv flag callback, so CM3 won't use port till it was reserved to CM3.

Stefan.