Fan not recognized

Will Liang (梁永鉉) Will.Liang at
Thu Jul 18 16:18:32 AEST 2019


You want to use two PWMs to control seven fans, but I found eight PWMs (PWM1~PWM8) in your hwmon folder.
There is a problem with your fan settings on device tree.

You can reference the following documentation in your project, which explains how to define fans at the device tree.


From: openbmc [ at] On Behalf Of AKASH G J
Sent: Wednesday, July 17, 2019 6:23 PM
To: openbmc at
Subject: Fan not recognized

Hi All,

I am using a server board with BMC Aspeed AST-2500 and BMC firmware with zaius configuration. 

Seven fans are connected to the board and we are using PWM0 to control first four fans and PWM1 to  control remaining fans.

root at zaius:ls /sys/class/hwmon/hwmon0
device fan4_input fan8_input pwm2 pwm6 uevent
fan1_input fan5_input name pwm3 pwm7
fan2_input fan6_input of_node pwm4 pwm8
fan3_input fan7_input pwm1 pwm5 subsystem

Even changing values of pwm1 and pwm2 to 0 or 127, the speed of the fan is not changing.

Also, reading the files fan1_input showing error.

Thanks in advance.

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