Re: [PATCH 6/7] netdev: octeon-ethernet: Add Cavium Octeon III support.

[David Daney]

On 11/02/2017 09:10 AM, Andrew Lunn wrote:
> On Thu, Nov 02, 2017 at 08:55:33AM -0700, David Daney wrote:
> > On 11/02/2017 05:43 AM, Andrew Lunn wrote:
> > [...]
> > > > +
> > > > +		i = atomic_inc_return(&pki_id);
> > > > +		pki_dev = platform_device_register_data(&new_dev->dev,
> > > > +							is_mix ? "octeon_mgmt" : "ethernet-mac-pki",
> > > > +							i, &platform_data, sizeof(platform_data));
> > > > +		dev_info(&pdev->dev, "Created %s %u: %p\n",
> > > > +			 is_mix ? "MIX" : "PKI", pki_dev->id, pki_dev);
> > >
> > > Is there any change of these ethernet ports being used to connect to
> > > an Ethernet switch. We have had issues in the past with these sort of
> > > platform devices combined with DSA.
> >
> > There are only two possibilities.  The BGX MACs have a multiplexer that
> > allows them to be connected to either the "octeon_mgmt" MIX packet
> > processor, or to the "ethernet-mac-pki" PKI/PKO packet processor.  The SoCs
> > supported by these drivers do not contain any hardware that would be
> > considered an "Ethernet switch".
>
> Hi David
>
> I was thinking of an external Ethernet switch. You generally connect
> via RGMII to a port of the switch.

OK, now I think I understand.  Yes, the MAC can be hardwired to a 
switch.  In fact, there are system designs that do exactly that.

We try to handle this case by not having a "phy-handle" property in the 
device tree.  The link to the remote device (switch IC in this case) is 
brought up on ndo_open()

There may be opportunities to improve how this works in the future, but 
the current code is serviceable.

> http://elixir.free-electrons.com/linux/v4.9.60/source/Documentation/networking/dsa/dsa.txt
>
> 	Andrew