PCIe Card not accessible

Technical Support
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1

After installing a new custom image on a Apalis imx8 module via recovery mode, an attached PCIe module is no longer accessible. I can confirm that the same image installed in a different imx8 module allows access to the PCIe module. So I don’t believe this is to be an image issue.

Having looked at “/sys/kernel/debug/gpio” on the two modules I can see a difference:

Working module:
gpio-346 (MXM3_15/GPIO7 |regulator-pcie-switc) out hi
gpio-446 ( |PCIe reset ) out hi

Non-working module:
gpio-346 (MXM3_15/GPIO7 |regulator-pcie-switc) out lo
gpio-446 - not listed

Does the PCIe regulator switch being “lo” prevent access to the PCIe module?
If so, what can cause it to switch position (e.g. h/w fault)?
How do I switch it back to hi?
Is it safe to do so without fear of damaging hardware?

Neil

2

Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!

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Hello,

Thank you for reaching out with your question about the PCIe interface on the Apalis iMX8. It seems you’re encountering issues related to the PCIe regulator switch.

  1. Indeed, if the PCIe regulator switch is set to low, it can prevent access to the PCIe module. The PCIe interface requires a properly configured power supply to function correctly.

  2. The Apalis iMX8 utilizes a vpcie-supply regulator that must be enabled for the PCIe interface to operate effectively. If this regulator, often referred to as reg_pcie_switch, is not configured or enabled properly, the PCIe interface will not function.

  3. Key aspects of the PCIe interface configuration on the Apalis iMX8 include:

    • PCIe controller configuration
    • Power supply (vpcie-supply) configuration
    • Reset signal handling

To address this issue, you might consider the following steps:

  • Verify the device tree configuration to ensure it is correct for your PCIe interface.
  • Test with a reference minimal image to determine if the issue persists.

Before making any changes, it’s important to review your hardware configuration and consult the carrier board documentation to ensure everything is set up correctly.

I hope this helps you resolve the issue with your PCIe interface. If you have further questions, feel free to ask.

Best regards,
Toradex AI Assistant.

3

Hi @nclark

So… what are the OS versions before and after the update ?? :sweat_smile: