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I've got a Thinkpad P50 running the latest version of Debian stretch. My desktop environment is mate.

I'm unable to control my laptop's backlight through any means. There are no backlight interfaces listed in /sys/class/backlight/, and I'm not sure which devices in /sys/devices/ would be the correct device to use.

$ inxi -G
Graphics:  Card: NVIDIA GM107GLM [Quadro M1000M]
           Display Server: X.Org 1.19.2 drivers: modesetting,nouveau (unloaded: fbdev,vesa)
           Resolution: 1920x1080@60.02hz, 2560x1440@59.95hz
           GLX Renderer: Gallium 0.4 on NV117 GLX Version: 3.0 Mesa 13.0.6

Output of find /sys/ -type f -iname '*brightness*':

/sys/devices/pci0000:00/0000:00:1c.2/0000:04:00.0/leds/phy0-led/max_brightness
/sys/devices/pci0000:00/0000:00:1c.2/0000:04:00.0/leds/phy0-led/brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::thinkvantage/max_brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::thinkvantage/brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::standby/max_brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::standby/brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::thinklight/max_brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::thinklight/brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::power/max_brightness
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::power/brightness
/sys/devices/platform/i8042/serio0/input/input0/input0::capslock/max_brightness
/sys/devices/platform/i8042/serio0/input/input0/input0::capslock/brightness
/sys/devices/platform/i8042/serio0/input/input0/input0::scrolllock/max_brightness
/sys/devices/platform/i8042/serio0/input/input0/input0::scrolllock/brightness
/sys/devices/platform/i8042/serio0/input/input0/input0::numlock/max_brightness
/sys/devices/platform/i8042/serio0/input/input0/input0::numlock/brightness
/sys/module/video/parameters/brightness_switch_enabled
/sys/module/thinkpad_acpi/parameters/brightness_enable
/sys/module/thinkpad_acpi/parameters/brightness_mode

Any ideas on how to get my backlight working?

  • What about xbacklight? It goes via the X server, not via /sys, and the X server has its own access to the display. Which GPU driver are you using (nv, nvidia, nouveau, …)? – Gilles Dec 18 '17 at 21:24
  • @Gilles I'm using nouveau. xbacklight returns 'No outputs have backlight property' – Connor Dec 18 '17 at 21:36

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