DS160PR410: Can retimer can help in easing enumeration?

Hi Poh,

Are you planning on using the DS160PT801 8-lane fourth generation PCIe retimer for this application?  Note it isn't pin compatible with the DS160PR810. 

Can you explain more about what you mean by enumeration and RX detection at the transmitter and provide a block diagram of the application?

Best Regards,

Nick

Hi Nick

We are having Enumeration problem with our PCIe setup where HOst is connected to FPGA(end-point) via fiber.
Setup has 1-Channel:
Host to Point-A is Electrical
Point-A to Point-B is optical
Point-B to FPGA is Electrical

Enumeration is way Host assigning BDF number to End Point Device with Vendor ID details upon Boot-Up
This Enumeration is successful if the connections are Electrical between Host to FPGA
When Optical Connection(FIBER) path come in between The host and FPGA, it is unable to detect FPGA details.

Redriver is refered to compensate the possible link losses, It is referred that Retimers are also PCI Protocol Compliance(I mean they can understand PCIe protocol) during DETECT, POLLING, CONFIGURE states...correct me if else case.

We hope that prefering Retimer in setup with optical link will resolve the issue..
Could you comment/ guidelines on above problem

Thankyou,
BAPAYYAK

Hi Bapayyak,

Thank you for the description of the case. You are correct about PCIe retimers. 

Can you share a schematic of the application? I'll add you as a friend so you can send it through direct message.

Is the redriver between B and the FPGA or is it between A and the Host?

Best Regards,

Nick

Hi Nick,
thankyou for the response.

The setup is already having two REDRIVERS. One between Host and Point-A; 2nd between Point-B and FPGA bidirectional.
Electrically Enumeration for Gen1, Gen2, Gen3 were attempted and was successful for Data Transfer too.
When we bring optics into setup even upon reboot we can't see FPGA details. So we are experimenting with Gen1 for now.

What if we replace Redriver with Retimer.
will this resolve FPGA enumeration.

thankyou,
BAPAYYAK

Hi Bapayyak,

Before looking at a retimer, can you attempt to force the redrivers into acting as a buffer with equalization to bypass RX detect? That would mean setting the RX_DET pin of the redrivers to L3 (59k ohms to ground) or you can set this setting in the GUI via SMBus.

Best,

Nick