Unstable link-up while Connecting iMX6 PCIe EP and PC RC

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Unstable link-up while Connecting iMX6 PCIe EP and PC RC

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gsp
Contributor I

Hello.

I am trying to connect sabre-lite and PC via PCIe.

The problem link up bit repeats the connection and disconnection.

- link up bit : 48.9.12 Debug Register 1 (PCIE_PL_DEBUG1) (located at Offset: 0x700 + 0x2C) --- [36]: xmlh_link_up LTSSM reports PHY link up

Also, there is any thing detected in PC neighter with Linux or Windows.

What I did for for connecting sabre-lite is:

1) For physical connection, I used a PCI connector and connected with RX-TX are reversed status.

2) Enabled PCIe EP mode in kernel config, using SD card for booting.

3) Changed PCIe reference clock according to '49.4.1.2 Reference Clock Frequency Selection' in RM, and this i.MX6Q: Using an external reference for PCIe link.

    I didn't modify the ENET PLL related part. I just modified PHY_MPLL_OVRD and PHY_ATEOVRD part.


The problem in link-up is:

1) On booting, log shows "PCIe EP: link up." message.

2) However, PC detects anything in linux or windows.

3) I used memtool to check 0x01FFC728 address, and it repeats link connection and disconnection.

In this case, what should I check more ?

Is there anyone who have successfully connected PC and iMX6 ?



Thank you in advance

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igorpadykov
NXP Employee
NXP Employee

Hi GieSeo

probably signal is too weak, reason can be

long cable. In general one can try to force i.MX6 to Gen1 mode

How to force iMX6 PCIe into Gen 1 mode | Freescale Community


Regarding checking from PC side one can look at


PCI-SIG - Training Materials


Best regards

igor