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magladko
Asked: 2024-09-21 05:54:20 +0800 CST

Cannot overwrite value under /sys/class/power_supply/CMB0/charge_control_end_threshold - Ubuntu 22.04 (6.8.0-45-generic)

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Some time ago I have created a simple script that will setup a battery charge limit on my laptop according to documentation.

I even modified crontab, so that it would remain between boots.

However, I think from some short time (maybe a day or two) I have noticed it stopped working. When I try to modify the /sys/class/power_supply/CMB0/charge_control_end_threshold it just reverts to 0 (does not matter if I run sudoedit or any other method)

I have previously noticed this behavior with different features described in the documenation page, but I just assumed they were not supported in a way.

Any comment or insight would be appreciated.

$ echo 80 | sudo tee /sys/class/power_supply/CMB0/charge_control_end_threshold 
[sudo] password for kornel: 
80
kornel@kornel-LG:~$ cat /sys/class/power_supply/CMB0/charge_control_end_threshold 
0

(as a note I have an LG Gram laptop)

kernel

1 Answers

  1. Best Answer

    That's a known kernel bug. You need at least kernel version 6.10.7. Refer to: https://github.com/linrunner/TLP/issues/747

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