Part Number: DS320PR822
Hello,
I am using two DS320PR822 devices as redriver/mux in a PCIe design.
System architecture:
- 1 PCIe controller
- 2 possible PCIe endpoint devices
- PCIe x4 interface
- Two DS320PR822: one for the TX path (controller → device) and one for the RX path (device → controller)
The redrivers are used to route the PCIe lanes to one of the two endpoints.
Issue:
When checking with the lspci command, the PCIe device is detected as x2 instead of x4.
To isolate the issue, I removed the redrivers and directly connected the inputs to the outputs with wires. In this configuration, the link correctly trains to x4, suggesting the issue is related to the DS320PR822.
Configuration:
The devices are used in pin-strap mode (1kR pull-down on MODE pin)
- PD0 and PD1 tied to GND (device enabled)
- SEL0 and SEL1 tied to GND (controller connected to device 1)
- EQ and gain set to default values
RX detection:
I tested the following modes:
- “Outputs polls until 3 consecutive valid detections” with an 8.25 kR pull-down
- “Tx polls every 150 µs until valid termination is detected” with RX_DET floating
The issue remains the same in both cases.
Could you advise on possible causes for losing two lanes in this configuration or any recommended settings for a PCIe x4 application?
