ttm_round_pot
extern size_t ttm_round_pot(size_t size);
size += ttm_round_pot(struct_size);
size += ttm_round_pot(npages * sizeof(void *));
size += ttm_round_pot(sizeof(struct ttm_tt));
size += ttm_round_pot(struct_size);
size += ttm_round_pot(npages * (2*sizeof(void *) + sizeof(dma_addr_t)));
size += ttm_round_pot(sizeof(struct ttm_dma_tt));
EXPORT_SYMBOL(ttm_round_pot);