LS1046A PCIe x2 Lane assignment

GyM — Mon, 15 Jan 2024 15:32:24 GMT

Hello,

We are building a custom board and need a PCIe link (Gen1, 2.5Gbps)) which can support either PCIe x1 or PCIe x2.

From the LS1046A Reference Manual (rev.3, 08/2021), in Table 31-2, we can configure PCIe.3 x1 to use:

- SERDES C (RX2/TX2) with SRDS_PRTCL_S2= 5559, 0559 or 5A59

- SERDES C (RX3/TX3) with SRDS_PRTCL_S2= 5506, 0506 or 5A06

Which means that for a x1 Link, we can connect either C or D to lane 0 of the other device.

In PCIe x2, neither the other device nor the LS1046A supports lane reversal. In the LS1046ARM (section 25.6.1.2, Table 25.6 and below), it states that: "The x2 controller does not support lane reversal." and the table says that for x2 link Lane 0 is 0 and Lane 1 is 1.

So if we use SRDS_PRTCL_S2= 5577 for PCIe.3 x2, which of C or D is Lane 0 to be connected to the Lane 0 of the other device ?

Re: LS1046A PCIe x2 Lane assignment

Oswalag — Wed, 17 Jan 2024 20:38:56 GMT

Hello,

Lane 0 - C

Lane 1 - D

Have a nice day!!

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LS1046A PCIe x2 Lane assignment

Re: LS1046A PCIe x2 Lane assignment