Re: [RFC PATCH vN net-next 2/2] net: mscc: ocelot: add support for VSC75XX SPI control

quoted

This function seems out of place. Why would SPI access change what the
ports are capable of doing? Please split this up into more
patches. Keep the focus of this patch as being adding SPI support.

What is going on is that this is just the way in which the drivers are
structured. Colin is not really "adding SPI support" to any of the
existing DSA switches that are supported (VSC9953, VSC9959) as much as
"adding support for a new switch which happens to be controlled over
SPI" (VSC7512).
The layering is as follows:
- drivers/net/dsa/ocelot/felix_vsc7512_spi.c: deals with the most
  hardware specific SoC support. The regmap is defined here, so are the
  port capabilities.
- drivers/net/dsa/ocelot/felix.c: common integration with DSA
- drivers/net/ethernet/mscc/ocelot*.c: the SoC-independent hardware
  support.

Hi Vladimir

I took a quick look at the data sheet. It says in section 2.1.5
Management:

  External access to registers through PCIe, SPI, MIIM, or through an
  Ethernet port with inline Microsemi’s Versatile Register Access
  Protocol (VRAP)

So maybe the basic 7512 support should be separate from how you access
the registers, so that somebody can later add MMIO or MDIO support?

    Andrew

P.S.

I did not know about VRAP. Marvell has something similar. It would be
nice to put together some shared generic code to support
this. Statistics would really benefit from it.