Extend smc911x to support LAN921x chips - differences?

[Guennadi Liakhovetski <g.liakhovetski@gmx.de>]

Hi,

I have to support the LAN9215 chip from SMSC under Linux. Of course, there 
is the manufacturer provided smsc911x driver, that supports both chip 
families, but I would prefer to extend the mainline smc911x driver to also 
support 921x. I have both datasheets, they are freely downloadable from 
SMSC site, and I have both drivers, but they are absolutely different. To 
make my decision and the work easier - maybe someone knows from the top of 
their head, what the relevant differences between the chips are?

The vendor driver does not really differentiate between the chips. It does 
read the chip version, and sets the "generation" variable, but then that 
variable is only used once to rule out the oldest chips, which anyway are 
not supported by smc911x. So I tried the in-kernel driver with only added 
chip IDs added, it can access registers, read and write the MAC-address, 
interrupts are generated too, but so far I see nothing on the wire, and 
the PHY reports "link down".

Thanks
Guennadi
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Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer