Kernel DT overlay

[NixiElectra]

Hello, I have questions related with overlay. I'm using Radxa Zero 3W and in the /boot/armbianEnv.txt it has overlay_prefix=rk35xx.

I want to use this overlay /boot/dtb/rockchip/overlay/radxa-zero3-disabled-wireless.dtbo. If I cat /boot/boot.cmd it read the overlays with this line ${overlay_prefix}-${overlay_file}.dtbo.

It means if I add overlays=disabled-wireless in /boot/armbianEnv.txt, it will not find the dtbo right?

So my questions are,

1. Can I manually edit the overlay_prefix to radxa-zero3?

2. If can then will that has impact on the feature, eg kernel upgrade or anything?

[robertoj]

It would be better if you make a copy of the dtbo from the original folder and name, to the overlays-user folder, then use the user_overlays parameter in armbianEnv.txt to add it.

 

In general, a DTBO copied from one SBC to another, will only work if the Radxa Zero 3W and the Radxa Zero 3 share the same:

* CPU chip

* chip pinout to the wireless chip

* wireless chip

* nothing else extra or missing interfering with the chip-wifi channel

 

It is always better to have the DTS (source code of DTBO), so you have full awareness of what it does, and compile with armbian-add-overlay

 

You can try it, then if you don't like the result, disable the dtbo with the user_overlays parameter.  ... and report whether it works or not.

 

When the kernel is upgraded, you may get a better support of the chip (if the Radxa or wifi software engineers have done something toward it)

 

 

When you upgrade kernel, the same DTBO can be used to patch the SBC DTB... unless there's a change in kernel module parameters (rare).