So I can see there is this post, but you never got back to it.
And I would like to know the same, especially regarding this point:
“BTW, I would also like to confirm whether MGBE supports 100M/1000M applications. Thanks!”
I can see that this is stated in the datasheet
My understanding is that the lowest supported data rate is 2.5 Gbps, while the line rate cannot go below 5 Gbps.
In that case, if a switch or adapter is connected to the QSFP port (MGBE controller) and communicates with the MGBE at a 5 Gbps line rate, would it then be possible to connect a 1 Gbps device to that switch and have it operate correctly?
Or is the MGBE fundamentally unable to support anything below 2.5 Gbps, regardless of what is connected on the other side?