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Troubleshooting Device Tree Overlay Application
Thank you for the additional details. Let’s troubleshoot your overlay application systematically.
1. Verify Overlay Files Exist
First, check if your overlay files are actually present in the correct location (1):
$ ls /boot/overlays
The overlays should be available as .dtbo files in this directory. If they’re not present, the overlay application will fail silently (1).
2. Check Current Device Tree Information
Use the tdx-info tool to check your current device tree configuration (2):
# sudo tdx-info -dt
This will show you the currently enabled device tree and any applied overlays (2).
3. Verify U-Boot Environment Variables
Check your current U-Boot environment to ensure the overlay mechanism is properly configured. You can examine this from Linux:
# fw_printenv | grep overlay
# fw_printenv | grep fdt
4. Enable Overlay Debug Messages
To get more verbose output about overlay loading, you can check the full boot log:
# dmesg | grep -i "overlay\|dtb\|fdt"
Also check for any device tree related messages:
# dmesg | grep -i "device.tree"
5. Alternative Overlay Application Method
If the overlays.txt file method isn’t working, you can try setting the overlay directly in U-Boot environment (1). From Linux, you can modify the U-Boot environment:
# fw_setenv fdt_overlays "imx95-19x19-verdin-lt8912.dtbo"
# reboot
6. Verify Overlay Compatibility
Ensure your overlay is compatible with your current BSP version. Device tree overlays must be written for the correct kernel version, which depends on the BSP you’re using (3).
7. Check for Pre-enabled Overlays
Some overlays might be pre-enabled by default and could conflict with your custom overlay (1). Check if there are any pre-enabled overlays that might be interfering.
8. Manual Overlay Loading Test
You can test if overlay loading works at all by trying to load a known working overlay manually. For SMARC iMX95, you should have access to several pre-built overlays (1).
9. Boot Partition Location
Ensure you’re editing the correct overlays.txt file. The location might vary depending on your setup. Try checking:
# find /boot -name "overlays.txt" -type f
# find /media -name "overlays.txt" -type f
10. Recovery Option
If an overlay breaks the boot process, you can disable overlay loading by setting (4):
# fw_setenv skip_fdt_overlays 1
This will bypass overlay loading entirely, allowing you to boot and fix the configuration.
Expected Behavior
When overlays are successfully applied, you should see messages in the boot log indicating the overlay loading process. The absence of any overlay-related messages in dmesg suggests the overlay loading mechanism isn’t functioning properly.
If none of these steps resolve the issue, there might be a fundamental problem with the overlay loading mechanism in your BSP version, or the overlay files might not be compatible with your specific hardware revision.
Best regards, Toradex AI Assistant.
