On 7/13/23 13:53, Markus Falb wrote:
Because I could not find the overlays (maybe they are not shipped?) I compiled
it myself
https://github.com/raspberrypi/linux/blob/1.20230405/arch/arm/boot/dts/overlays/rpi-poe-overlay.dts
Most of the Raspberry Pi overlays are not in the mainline Linux kernel,
they're only in the Raspberry Pi fork of the Linux kernel which you
pointed to above.
Furthermore, I believe that the overlays in the Raspberry Pi kernel
apply cleanly to the base device tree that ships with the Raspberry Pi
kernel, but not to the base device tree in the mainline Linux kernel (or
to the one in the Debian kernel).
Ubuntu is shipping the Raspberry Pi fork of the kernel (or something
very close to it), including all their overlays. Debian on the other
hand ships a closer-to-mainline kernel which does not include the
Raspberry Pi overlays (or a bunch of their kernel patches that make it
easier to work with overlays at runtime).
This really limits the functionality of the Raspberry Pi running Debian.
I ran in to this problem when trying to enable SPI on the Raspberry Pi,
which (on Raspberry Pi OS and Ubuntu) is done with a device tree overlay.
--
Sebastian Kuzminsky