DEVMEM_CHUNK_SIZE
res = request_free_mem_region(&iomem_resource, DEVMEM_CHUNK_SIZE,
DEVMEM_CHUNK_SIZE - 1;
DEVMEM_CHUNK_SIZE / (1024 * 1024),
mdevice->devmem_count * (DEVMEM_CHUNK_SIZE / (1024 * 1024)),