The in plat/imx/common/imx8_topology.c plat_core_pos_by_mpidr() do are greater-than instead of a greater-or-equal compare on the cluster_id and cpu_id.
if (cluster_id > PLATFORM_CLUSTER_COUNT ||
cpu_id > PLATFORM_MAX_CPU_PER_CLUSTER)
return -1;
should instead be:
if (cluster_id >= PLATFORM_CLUSTER_COUNT ||
cpu_id >= PLATFORM_MAX_CPU_PER_CLUSTER)
return -1;