# Brightness on Thinkpad L480



## laufdi (Jul 17, 2020)

On pressing Fn-F5 or Fn_F6 I get a delayed brightness change and kernel messages:


```
Jul 17 13:54:33 tp kernel: acpi_ec0: EcCommand: no response to 0x84
Jul 17 13:54:33 tp syslogd: last message repeated 1 times
Jul 17 13:54:33 tp kernel: acpi_ec0: GPE query failed: AE_NO_HARDWARE_RESPONSE
```

setting debug.acpi.ec.timeout to some higher value as suggested does not help, only delays everything even more.


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## Mjölnir (Jul 17, 2020)

The kernel module acpi_ibm(4) is very outdated, it works for older ThinkPads but for the newer Lenovo TPs it does not work well.  You can instead use graphics/intel-backlight.  If you have plenty of time, you may tinker to get a solution to use acpi_ibm(4) together with a devd(8) script.


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