I have piCore v15 aarch64 running on a CM5. I have a basic MIPI DSI display connected and it works with dtoverlay=vc4-kms-dsi-generic in my config.txt
However, no 3D acceleration:
tc@box:~$ glxinfo -display :0 |grep Accelerated
MESA-LOADER: glx: failed to open zink: driver not built!
MESA-LOADER: glx: failed to open drm-rp1-dsi: driver not built!
failed to load driver: drm-rp1-dsi
Accelerated: no
NB: drm_rp1_dsi is loaded and the errors go away if I set the environment variable MESA_LOADER_DRIVER_OVERRIDE=zink, however glxinfo tells me the OpenGL renderer is not zink but llvmpipe.
I was able to get acceleration working on a CM4 with piCore v13, a few years back, with dtoverlay=vc4-fkms-v3d, by adding some config files into /usr/local/share/X11/xorg.conf.d/ This fix loaded the glamoregl module, which provided the acceleration. Looking at the structure for v15, I see a 20-noglamor.conf in /usr/local/share/Xorg-3d/files so maybe that is no longer the way to go now we have a RP1 chip handling the GPU. I was probably cribbing from RaspberryPi OS, but there's not much for configuration in X server there on my CM5.
Any ideas on things I can try or should investigate would be much appreciated.