Hi,
I have a RockPi 4B coupled with a Hifiberry DAC+ Pro XLR. The Hifiberry wasn't designed for the RockPi, but it is in fact compatible with it. I know it, because I have got it working on Armbian, with the 4.4 BSP kernel for a while now. As far as I can remember, what is needed in order to get it to work, are compiling and installing a kernel module for the PCM5242 DAC chip and an overlay, in order to configure the RK3399's pins for the proper modes needed to talk to the DAC.
1. Can someone point me to the easiest way of doing the above, i.e. compiling a custom module and loading a custom device overlay, in libreELEC? Note that the PCM5242 is not supported by the Linux kernel, but, from what I remeber, the driver for the PCM512X chips, which are supported, can be used with some trivial changes. I'm not asking for help on modifying the driver code, just on building and loading the result on libreELEC.
2. I did write the overlay (.dtb) file for my current setup, but this is applicable to the 4.4 kernel and it needs substantial changes for newer kernels as far as I recall. (There was at least a substantial change in the relevant sound subsystem design in the 4.19 release of the kernel or somewhere around that time anyway.) Sadly (or perhaps mercifully, depending on how one looks at it) I don't remember anything about writing, compiling and loading device tree overlays any more. If someone has some experience with it and would be willing to help out, I'd be most grateful.
Thanks in advance,
Dimitris