Radxa Dragon Q6A: Device Tree Overlays

[eshcheglov]

Hello,

On the Radxa Q6A board, a list of extra DT overlays is provided to enable peripherals (like I2C, SPI, or UART): https://github.com/radxa-pkg/radxa-overlays/tree/main/arch/arm64/boot/dts/qcom/overlays

I tried the following steps without success:

1. Compiled .dtso into .dtbo using dtc, and placed the result into the /boot folder
2. Installed the kernel-devicetree package, which provides the /boot/qcs6490-radxa-dragon-q6a.dtb file
3. Added lines to the systemd-boot configuration. Note that I am forced to load the main devicetree, because otherwise the devicetree-overlay directive is ignored (according to the sd-boot documentation):

devicetree /qcs6490-radxa-dragon-q6a.dtb
devicetree-overlay /qcs6490-radxa-dragon-q6a-i2c0.dtbo

The result is nothing: /dev/i2c-0 does not appear, and there are no errors in the logs indicating a failed apply

I'm wondering how one can integrate these into the Qcom distro

Navin (@navinreddy23) maybe you have a clue?

[navinreddy23]

Hi Eugeny Shcheglov (@eshcheglov),

Please see the camera DTBO example on my gitlab repo.

It is sort of a convoluted way to apply DTBO. First extract the base, then merge it with the compiled DTS.
I had to create a new entry on systemd boot menu that uses the overlay.

But I have verified the camera to work on Dragon Q6A.

Please let me know if you have any questions.

[ricardosalveti]

While devicetree-overlay is available at https://uapi-group.org/specifications/specs/boot_loader_specification/, I don't think the support in systemd-boot ever landed, at least doesn't seem so when looking at the sources.

So the 'easiest' would indeed to generate a full device-tree based on the overlays you need, and use it as the main dtb.

[github-actions]

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