Jean-Christophe PLAGNIOL-VILLARD wrote:
On the EVK1100 board, the CPU (UC3A0512) is connected to the PHY via an RMII bus. This requires the CPU clock to be at least 50 MHz. Unfortunately, the chip on current EVK1100 boards may be unable to run at more than 50 MHz, and with the oscillator on the board, the closest frequency we can generate is 48 MHz.
IMHO It's a HW design error to not use the MII
Some people want to use the extra pins for other things...
Unfortunately, there are quite a few boards with early engineering samples around, and they have various issues. The chips that are in production are capable of running fast enough to support RMII.
This patch makes it possible to limit the macb to 10 MBit for this case. We are open for suggestions for other solutions.
I guest you may need to disable the phy auto config mode and force him to be see as a 10Mbps phy evenif it's a 10/100
No need to disable autonegotiation -- you still want to select between half an full duplex, for example. But you'll need to limit the available options to the ones that actually work.
That said, I kind of like Ben's suggestion -- it's a more general solution to all sorts of board/phy/chip/whatever limitations.
As for a better name, how about CONFIG_MACB_ADVERTISE?
Haavard