在 ThinkPad L480 上从 18.04 更新到 18.10 时，Elantech 触摸板停止工作。这意味着它根本不被识别。18.10第一次开机后出现这个问题
dmesg | grep -i elantech 显示以下错误：
[ 3.409043] psmouse serio1: elantech: assuming hardware version 4 (with firmware version 0x5f3001)
[ 3.427372] psmouse serio1: elantech: Synaptics capabilities query result 0x90, 0x18, 0x10.
[ 3.447275] psmouse serio1: elantech: Elan sample query result 00, 23, c8
[ 3.464905] psmouse serio1: elantech: Trying to set up SMBus access
[ 5.576149] elan_i2c 0-0015: 0-0015 supply vcc not found, using dummy regulator
[ 5.586505] elan_i2c 0-0015: failed …