It works with a following procedure.
1. comment out /etc/modprobe.d/blacklist.conf
# blacklist snd_pcsp
2. load pc speaker kernel module
$ sudo modprobe snd_pcsp
3. run beep with -e option
$ beep -e /dev/input/by-path/platform-pcspkr-event-spkr
It works with a following procedure.
1. comment out /etc/modprobe. d/blacklist. conf
# blacklist snd_pcsp
2. load pc speaker kernel module
$ sudo modprobe snd_pcsp
3. run beep with -e option
$ beep -e /dev/input/ by-path/ platform- pcspkr- event-spkr