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Original question:

AM5728: PCIe compliance testing

AM5728: PCIe link status

Lawrence Wong
Genius 14960 points
Part Number: AM5728

Customer trying to verifying status of PCIe link-up between AM57x EVM and PCIe NIC Card 

Could you verify which message should they use check to see the PCIe Gen 2 link status ?

 

    1. Just running “lspci” command, can they verify the PCIe Gen 2 link-up status ?

    1. Using lspci -vvv do they verify check “LinkCap” or “LinkCtl2” status as way to confirm link status?

  • 0
    TI__Guru*** 147056 points

    Hi Lawrence,

    LinkCap and LinkCtl2 do not reflect the link status. If lspci command lists the NIC card entry, it means the link is up. If lspci only lists one entry which is the PCI bridge, it means the link is down.

  • 0 in reply to Bin Liu
    TI__Genius 14960 points

    Bin,

    Here is what my customer is seeing.  Can you confirm if the AM57x  automatically reduces PCIe speed to 2.5GT when the GEN 2 link-up fail ?

     

    Test #1: Pcie link-up with NIC at 5GT.

    root@am57xx-evm:~# lspci

    00:00.0 PCI bridge: Texas Instruments Multicore DSP+ARM KeyStone II SOC (rev 01)

    01:00.0 Ethernet controller: Toshiba America Info Systems Device 021a

     

    AM57x:

    LnkCap: Port #0, Speed 5GT/s, Width x2, ASPM L0s L1, Exit Latency L0s <512ns, L1 <64us

    LnkSta: Speed 5GT/s (ok), Width x1 (downgraded)

    LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis

     

    Neutrino:

    LnkCap: Port #0, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <512ns, L1 <32us

    LnkSta: Speed 5GT/s (ok), Width x1 (ok)

    LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-

     

     

    Test #2: Pcie Fails to link-up with NIC due to no power is presented to NIC.
    root@am57xx-evm:~# lspci

    00:00.0 PCI bridge: Texas Instruments Multicore DSP+ARM KeyStone II SOC (rev 01)

     

    AM572x:

    LnkCap: Port #0, Speed 5GT/s, Width x2, ASPM L0s L1, Exit Latency L0s <512ns, L1 <64us

    LnkSta: Speed 2.5GT/s (downgraded), Width x1 (downgraded)

    LnkCtl2: Target Link Speed: 5GT/s, EnterCompliance- SpeedDis-

     

    Regards,

    Lawrence

  • 0 in reply to Lawrence Wong
    TI__Guru*** 147056 points

    Hi Lawrence,

    Lawrence Wong said:
    Here is what my customer is seeing.  Can you confirm if the AM57x  automatically reduces PCIe speed to 2.5GT when the GEN 2 link-up fail ?

    Yes, the PCI link negotiation starts from the lowest speed - 2.5GT, and sets to the highest successfully negotiated speed.

    In the test #2 you mentioned above, lspci command doesn't list the PCIe device, but you mentioned the NIC doesn't have power, so it is expected, isn't it?