#1029148 pwmconfig: DELAY=5 too low on a Lenovo Thinkpad T14s Gen3 AMD -> "no correlation"

#1029148#5
Date:
2023-01-18 15:32:28 UTC
From:
To:
Dear Maintainer,

The DELAY=5 seems to be too low for a Lenovo Thinkpad T14s Gen3 AMD. I'm
getting the "no correlation" message when pwmconfig tries to detect the
PWM->fan correlation.

Once I see the message "Testing pwm control hwmon6/pwm1 ..." I do
immediately hear the fan to go from its disengaged maximum of 4900 RPM
to 0 nearly instantly, however it seems it takes a while to get propagated
to /sys/class/hwmon/hwmon6/fan1_input.

In my tests DELAY=10 seems to be at the border, it usually works but
sometimes fails. DELAY=12 or greater seems to be reliable.

You can find a few example outputs (with some extra debug output lines
I had added) for various DELAY values below.

The UEFI System Firmware should be the latest available today (0.1.25
according to fwupdmgr).

Regards, Linus


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