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Participant
Participant
10,754 Views
Registered: ‎09-10-2012

Direct RGMII connectrion between two Zynq's.

Is it possible to connect two Zynq's with PS RGMII interface without PHY?

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Participant
Participant
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Registered: ‎03-09-2016

Hi

 


mistercoffee wrote:

It would seem you just can't get this interface working. As we are working on slightly different devices (88E6321 vs 88E6532) I decided to compare the datasheets. They are very similar, both 7 port gigabit ethernet switch, the main difference between the exact combination of port types. But I did notice a significant difference, which may just be the datasheet wording. 

 

If you look at the RGMII connection diagram (Fig 14, Page 46 for 88E6352, Fig 11 Page 43 88E6321) the wording is different. The 88E6352 says "Port 5 or 6 acting as a MAC" whereas the 88E6321 just says "Port 2, Port 5 or Port 6". This would indicate why you cannot get the switch working as a PHY. 


 

Firstly, thanks for your interests and efforts which are time consuming. I also looked into both datasheets and you are right that our devices actually very similar. when you look at the Figure 1 Top Level Block Diagrams of both switch 6352 and 6321, page5 and page6 respectively, you see that;

6352: P0-P1-P2-P3-P4 have 10/100/1000 PHY

            P4-P5 can have Serdes

            P5-P6 can be MAC or PHY Mode with Digital Interfaces

6352: P3-P4 have 10/100/1000 PHY

            P0-P1 have Serdes

            P2-P5-P6 can be MAC or PHY Mode with Digital Interfaces

 

That is, P5 and P6 are PHY-less MAC-to-MAC connection over digital interfaces. If the digital interface mode is selected RGMII then it is not needed to be PHY, which is pointed out in the datasheet pg43 of 6321: "Reduced Gigabit Media Independent Interface (RGMII) so that it can be directly connected to an external RGMII-based
Gigabit PHY or CPU". So, in our case the CPU is the Zynq-7045 and can be connected directly.

 


mistercoffee wrote:

You said you were looking at the 88E6111R MAC/PHY chip that is used on the ZC706 board. I did wonder about using this but was unsure whether the PHY interface would work because it usually interfaces to the transformer magnetics you would find in PHY connector rather than into another digital interface. You may want to also consider the MAX24287, which is an RGMII to SGMII converter. We used this on another design which had no ethernet switch.


 

Some considerations are needed when the connect two PHYs without transformer magnetics. There are some application-notes on the internet about those design needs about transformerless PHY connection. However, if the two PHYs are on the same PCB and have same power and ground connections, direct connections can be made and maybe some series capacitors needed when gigabit speed is needed.

 

However, those are all not important and needed anymore since we finally succeeded to work ethernet switch 88e6352!! Solutions has been made by using petalinux 2017.1 + macb-mdio patch for 2017.1 + proper device tree. Actually, correct/proper device tree configuration is important for what I made lots of test with different device tree configs.

 

Be sure, i will post detail solution what I did within 2-3 days, but for this please follow below link which I created before here;

https://forums.xilinx.com/t5/Embedded-Linux/zynq-and-marvell-dsa-88e6352-integration-device-tree/m-p/779400

 

thanks a lot again,

 

 

 

 

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Participant
Participant
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Registered: ‎03-09-2016

Hi,

 

You can find the solution steps info on the link below;

https://forums.xilinx.com/t5/Embedded-Linux/zynq-and-marvell-dsa-88e6352-integration-device-tree/m-p/787864#M21359

 

Our working on EMIO connected switch still continues. Since it uses the gmii2rgmii IP core, it could not work the solution way for MIO connected one. Maybe some gmii2rgmii related patch required. Anyway, I will also post the solution when it will be ended up.

 

thanks,

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Scholar
Scholar
2,077 Views
Registered: ‎04-04-2014


@idogan wrote:

Hi,

 

You can find the solution steps info on the link below;

https://forums.xilinx.com/t5/Embedded-Linux/zynq-and-marvell-dsa-88e6352-integration-device-tree/m-p/787864#M21359

 

Our working on EMIO connected switch still continues. Since it uses the gmii2rgmii IP core, it could not work the solution way for MIO connected one. Maybe some gmii2rgmii related patch required. Anyway, I will also post the solution when it will be ended up.

 

thanks,


Thanks very much, I will have a read.

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Participant
Participant
1,868 Views
Registered: ‎03-09-2016

Hi,

 

I have finished the 2 ethernet switches integration with GEM0 and GEM1. Updated information is given on the same link below;

https://forums.xilinx.com/t5/Embedded-Linux/zynq-and-marvell-dsa-88e6352-integration-device-tree/m-p/798867#M22142

 

thanks,

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