RE: [PATCH net-next 4/6] arm64: dts: fsl: ls1028a: Add Felix switch port DT node

[Claudiu Manoil]

Hi Andrew,

>-----Original Message-----
>From: Andrew Lunn <andrew@xxxxxxx>
>Sent: Friday, June 21, 2019 7:50 PM
>To: Claudiu Manoil <claudiu.manoil@xxxxxxx>
>Cc: David S . Miller <davem@xxxxxxxxxxxxx>; devicetree@xxxxxxxxxxxxxxx;
>Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx;
>Alexandru Marginean <alexandru.marginean@xxxxxxx>; linux-
>kernel@xxxxxxxxxxxxxxx; UNGLinuxDriver@xxxxxxxxxxxxx; Allan Nielsen
><Allan.Nielsen@xxxxxxxxxxxxx>; Rob Herring <robh+dt@xxxxxxxxxx>; linux-
>arm-kernel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: [PATCH net-next 4/6] arm64: dts: fsl: ls1028a: Add Felix switch port
>DT node
>
>On Fri, Jun 21, 2019 at 06:38:50PM +0300, Claudiu Manoil wrote:
>> The switch device features 6 ports, 4 with external links
>> and 2 internally facing to the ls1028a SoC and connected via
>> fixed links to 2 internal enetc ethernet controller ports.
>
>Hi Claudiu
>
>> +			switch@0,5 {
>> +				compatible = "mscc,felix-switch";
>> +				reg = <0x000500 0 0 0 0>;
>> +
>> +				ethernet-ports {
>> +					#address-cells = <1>;
>> +					#size-cells = <0>;
>> +
>> +					/* external ports */
>> +					switch_port0: port@0 {
>> +						reg = <0>;
>> +					};
>> +					switch_port1: port@1 {
>> +						reg = <1>;
>> +					};
>> +					switch_port2: port@2 {
>> +						reg = <2>;
>> +					};
>> +					switch_port3: port@3 {
>> +						reg = <3>;
>> +					};
>> +					/* internal to-cpu ports */
>> +					port@4 {
>> +						reg = <4>;
>> +						fixed-link {
>> +							speed = <1000>;
>> +							full-duplex;
>> +						};
>> +					};
>> +					port@5 {
>> +						reg = <5>;
>> +						fixed-link {
>> +							speed = <1000>;
>> +							full-duplex;
>> +						};
>> +					};
>> +				};
>> +			};
>
>This sounds like a DSA setup, where you have SoC ports connected to
>the switch. With DSA, the CPU ports of the switch are special. We
>don't create netdev's for them, the binding explicitly list which SoC
>interface they are bound to, etc.
>
>What model are you using here? I'm just trying to understand the setup
>to ensure it is consistent with the swichdev model.
>

Yeah, there are 2 ethernet controller ports (managed by the enetc driver) 
connected inside the SoC via SGMII links to 2 of the switch ports, one of
these switch ports can be configured as CPU port (with follow-up patches).

This configuration may look prettier on DSA, but the main restriction here
is that the entire functionality is provided by the ocelot driver which is a
switchdev driver.  I don't think it would be a good idea to copy-paste code
from ocelot to a separate dsa driver.

Thanks for the review.
Claudiu