使用v3.0固件，npu时好时坏，请问为什么

环境：rk3399pro，debian
使用rknn-tooklit中demo显示：
--> Init runtime environment
E Only support ntb mode on ARM64 platform. But can not find device with ntb mode.
E Catch exception when init runtime!
E Traceback (most recent call last):
E   File "rknn/api/rknn_base.py", line 815, in rknn.api.rknn_base.RKNNBase.init_runtime
E   File "rknn/api/rknn_runtime.py", line 170, in rknn.api.rknn_runtime.RKNNRuntime.__init__
E   File "rknn/api/rknn_platform_utils.py", line 307, in rknn.api.rknn_platform_utils.start_ntp_or_adb
E Exception: Init runtime environment failed!
Init runtime environment failed

使用rkapi中demo显示：
E NPUTransfer: Transfer interface open failed!, ret = -1
E RKNNAPI: rknn_init,  driver open fail!  ret = -1(ERROR_IO)!
rknn_init fail! ret=-3

但是有些时候又是可以顺利使用的，请问一下固件3.0是不是有问题，我想问下不适用固件3.0，怎么直接升级npu driver到1.6