d/patches: Enable dmabuf-heaps in Mobian patches
In order to allow the Librem5 use the libcamera softwareISP, which is again needed to make the camera work with Pipewire and thus a large number of apps.
The CMA variant is the import one, as it allows to allocate contiguous buffers which can potentially get imported into the GPU. SYSTEM is page based and not really needed, but might be useful for testing purposes.
While on it, drop CONFIG_CMA_SIZE_MBYTES
as it depends on CONFIG_X86
and thus doesn't make sense here.
This creates devices in /dev/dma_heap/
which by default have 600
permissions - i.e. are only usable by root by default.
Edited by Robert Mader