hello judy.wang,
this is a known issue that rpm_measured is return zero even it’s running at full speed.
for example,
# cat /sys/class/hwmon/hwmon1/cur_pwm
255
# cat /sys/class/hwmon/hwmon1/rpm_measured
0
that’s due to fan driver is looking-up pwm_rpm_table to configure PWM signals to determine the fan speed; please check cur_pwm for its RPM values.
for example, the RPM is 11000 while PWM is 255.
$ cat /sys/class/hwmon/hwmon1/pwm_rpm_table
(Index, RPM, PWM, RRU, RRD)
(0, 0, 0, 40, 40)
(1, 1000, 80, 2, 2)
(2, 2000, 120, 1, 1)
(3, 3000, 160, 1, 1)
(4, 4000, 255, 1, 1)
(5, 5000, 255, 1, 1)
(6, 6000, 255, 1, 1)
(7, 7000, 255, 1, 1)
(8, 10000, 255, 1, 1)
(9, 11000, 255, 1, 1)