Roshi's Ramblings

Documenting things I document

Recently I've been having issues with the backlight on my Lenovo W530 running Rawhide. Sometimes it would work, but didn't most of the time. It was really a minor issue - so I didn't sweat it much (although it really hurt battery life). I finally filed a bug against it and got some feedback I thought might be useful to others (since you might not find the bug report with google-troubleshooting).

Thanks to poma for putting this list together!

PS - The option that works for me is booting with "acpi_backlight=vendor"

// Roshi

Options to try to fix your backlight issues:

Some of them are the following:

acpi_osi="!Windows 2012"

Kernel Param Reference

The story of _OSI(Linux)

$ modinfo video
parm:           use_native_backlight:int
acpi_backlight= [HW,ACPI]
            If set to vendor, prefer vendor specific driver
            (e.g. thinkpad_acpi, sony_acpi, etc.) instead
            of the ACPI video.ko driver.
$ modinfo thinkpad_acpi
parm:           brightness_enable:Enables backlight control when 1, disables when 0 (uint)

ThinkPad-ACPI Reference

Disabling backlight driver

Section "Device"
  Identifier "devname"
  Driver "intel"
  Option "Backlight" "intel_backlight"

Intel Issues

man 4 intel

Option "Backlight" "string" Override the probed backlight control interface. Sometimes the automatically selected backlight interface may not correspond to the correct, or simply most useful, interface available on the system. This allows you to override that choice by specifying the entry under /sys/class/backlight to use.

man 1 xrandr --brightness brightness

man 1 xbacklight

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