How to upload by Atmel ICE via PlatformIO in VS Code?

I want to upload sketch in PlatformIO for VS Code, but it just prompt:

before I added “upload_protocol = atmelice_isp”, it prompted:

avrdude: ser_open(): can’t open device “unknown”: ???

How to solve it ? My Atmel ICE has been verified and rightly configured. And it could be used normally in Atmel Studio.

I have added these in platformio.ini

upload_flags =


; edit this line with valid upload port

upload_port = SERIAL_PORT_HERE

Is it OK?