$ setserial /dev/ttyUSB0 -G
Cannot get serial info: Inappropriate ioctl for device
这个错误是什么意思？stty工作正常：
$ stty -F /dev/ttyUSB0
speed 9600 baud; line = 0;
eof = ^A; min = 1; time = 0;
-brkint -icrnl -imaxbel
-opost -onlcr
-isig -icanon -iexten -echo -echoe -echok -echoctl -echoke