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OV9281 DToverlay not loading kernel module

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zharr:
Hello,
I've been using piCore 13 with the OV9281, but with piCore 14 the module is not loaded even with
--- Code: ---dtoverlay=ov9281,media-controller=0
--- End code ---
in config.txt. It has been verified to be not loaded after boot with lsmod. I was able to manually load it with
--- Code: ---sudo modprobe ov9281
--- End code ---
but this does not make the /dev/video0 node appear. I've also tried piCore 15 (though I won't be able to use it long term due to missing packages for armv6 - Pi Zero 1). Same behaviour here, except the module has also been renamed to ov9282.ko (I expect the functionality would remain the same, but it doesn't work).
Perhaps this is not piCore related, but I cannot find any information about this for normal Raspberry Pi OS, which I would expect if it was a common issue.
Any ideas on how to further debug this? I'm not sure which dtbo the device tree file would have been compiled from and how to check them, but am willing to debug myself if pointed the right way.
Thanks!

PS: I'm currently exploring just cutting out the OV9281 driver altogether since it's too niche to rely on and I do some custom I2C commands already anyway. Just using base bcm2835-unicam would work too, though I am unsure if I can use it directly just to receive raw frames and setup the sensor via I2C in userspace. If anybody got any info on how to make unicam expose the raw data on /dev/video0, that's be amazing, too.

patrikg:
Have seen that config.txt has some groups in some os'es, maybe you have typed in dtoverlay at the wrong line. The groups are for what rpi model it's for.
and the gruop [ALL] is for them all.

Paul_123:
The overlay does not load the module, it purely configures the system.  The kernel has to detect the module to get the module loaded.

The fact that /dev/video does not get created after a manual modprobe probably mean something is no longer working or supported.   Or another dependency.

zharr:
Thanks both of you. It is under [ALL], and yeah I assume something broke. The camera system especially seems to be changing every few months, quite frustrating. Sadly I need to update because of wifi not being reliable on 13.

Will keep a lookout to eliminate the OV9281 driver as a dependency altogether and do it in userspace. No leads still.

zharr:

--- Quote from: Paul_123 on June 12, 2025, 04:43:55 PM ---The overlay does not load the module, it purely configures the system.  The kernel has to detect the module to get the module loaded.

The fact that /dev/video does not get created after a manual modprobe probably mean something is no longer working or supported.   Or another dependency.

--- End quote ---
I'm having trouble finding any hints on developing kernel modules for piCore, can't even find a way to get the kernel headers.
Is it possible to develop and debug the modules on the device without recompiling the whole kernel?

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