Hi Russell,

On Mon, Mar 19, 2018 at 01:18:05PM +0000, Russell King - ARM Linux wrote:

On Mon, Mar 19, 2018 at 02:10:09PM +0100, Antoine Tenart wrote:

quoted

On 7k/8k you have the following scheme for 10G only interfaces:

   MAC -- Comphy -- PHY -- SFP cage -- ...

Or

   MAC -- Comphy -- SFP cage -- ...

The comphy provides serdes lanes, and can be configured in various
modes (SGMII, 2500SGMII, 10GKR...).

Right - the correct mode is dependent on the SFP module plugged into
the cage.  Trying to describe this by ignoring the SFP cage isn't
going to work out well for end-user functionality, though is fine if
you're just hacking a configuration to test (which would not be
suitable for mainline kernels!)

As I've recently replied to Yan, this is a configuration I haven't
tested yet, and it's entirely possible that phylink may need some
tweaks for it.

What you have is a very similar setup to what is on Clearfog with
its SFP cage, where the SFP cage is connected directly to the
Armada 388.  That only has to deal with 2500base-X / 1000base-X /
SGMII and not 10G.

What I want is to avoid hacks as much as possible here - if there is
a short-coming with SFP/phylink here, we need to address that
properly.

OK. So the proper solution would be to properly describe the SFP cages
in the device tree (and check if phylink deals with it nicely).

I'll update the patches in this way.

Thanks for the feedback,
Antoine

-- 
Antoine T?nart, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com