All overlays and their overrides are documented in the README for overlays, and are also available via "dtoverlay -h <overlay-name>"
"dtoverlay=cma,cma-320" will allow you to change the CMA heap size without vc4-kms-v3d. Do note the help text warns of potential interactions with other overlays (eg vc4-kms-v3d), so it should only be used as a last resort.
However I would query what this display is that won't work with vc4-kms-v3d. I'd guess at a DPI display, and you've got a load of dpi_timings and similar entries in config.txt, and the vendor no longer provides any support.
There's a white paper at https://pip.raspberrypi.com/categories/ ... isplay.pdf that covers converting those legacy commands into parameters for dtoverlay=vc4-kms-dpi-generic for use in the new display stack. The new stack is the only option for Pi5, so adapting will be required if switching to the newer platform.
Memory says that using cma=X on the kernel command line changes the name of the heap, so the dma_buf heap allocators in libcamera may not play nicely with it. The dtoverlay is the recommended approach.
"dtoverlay=cma,cma-320" will allow you to change the CMA heap size without vc4-kms-v3d. Do note the help text warns of potential interactions with other overlays (eg vc4-kms-v3d), so it should only be used as a last resort.
However I would query what this display is that won't work with vc4-kms-v3d. I'd guess at a DPI display, and you've got a load of dpi_timings and similar entries in config.txt, and the vendor no longer provides any support.
There's a white paper at https://pip.raspberrypi.com/categories/ ... isplay.pdf that covers converting those legacy commands into parameters for dtoverlay=vc4-kms-dpi-generic for use in the new display stack. The new stack is the only option for Pi5, so adapting will be required if switching to the newer platform.
Memory says that using cma=X on the kernel command line changes the name of the heap, so the dma_buf heap allocators in libcamera may not play nicely with it. The dtoverlay is the recommended approach.
Statistics: Posted by 6by9 — Wed Feb 26, 2025 11:44 am