net: phy: Dealing with 88e1543 dual-port mode

[Maxime Chevallier]

Hi Andrew,

On Thu, 19 Nov 2020 16:16:41 +0100
Andrew Lunn <andrew at lunn.ch> wrote:

>Hi Maxime
>
>> The way this works is that the PHY is internally configured by chaining
>> 2 internal PHYs back to back. One PHY deals with the Host interface and
>> is configured as an SGMII to QSGMII converter (the QSGMII is only used
>> from within the PHY), and the other PHY acts as the Media-side PHY,
>> configured in QSGMII to auto-media (RJ45 or Fiber (SFP)) :
>> 
>>                 +- 88e1543 -----------------------+
>> +-----+         | +--------+          +--------+  |  /-- Copper (RJ45)
>> |     |--SGMII----| Port 0 |--QSGMII--| Port 1 |----<
>> |     |         | +--------+          +--------+  |  \--- Fiber
>> | MAC |         |                                 |
>> |     |         | +--------+          +--------+  |  /-- Copper (RJ45)
>> |     |--SGMII----| Port 2 |--QSGMII--| Port 3 |----<
>> +-----+         | +--------+          +--------+  |  \-- Fiber
>>                 +---------------------------------+  
>
>Does this mean you need a dual port MAC as well?
>
>Do we need to configure the MUX in the MAC?

No, it's my schematic that is misleading in that case :) The 2
ports are independent of each other. There isn't any configuration on
the MAC part for that setup.

Thanks,

Maxime



-- 
Maxime Chevallier, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com