[SOLVED] Built-in brightness control doesn't work on laptop

[94d4a788df]

As the title says, the built-in brightness control doesn't work. Output from inxi:

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System:    Kernel: 5.4.0-42-generic x86_64 bits: 64 compiler: gcc v: 9.3.0 Desktop: Cinnamon 4.6.6 
           Distro: Linux Mint 20 Ulyana base: Ubuntu 20.04 focal 
Machine:   Type: Laptop System: Acer product: TravelMate 5740 v: V1.14 serial: <filter> 
           Mobo: Acer model: TravelMate 5740 v: V1.14 serial: <filter> BIOS: Acer v: 1.14 date: 09/13/2010 
CPU:       Topology: Dual Core model: Intel Core i5 M 430 bits: 64 type: MT MCP arch: Nehalem rev: 2 L2 cache: 3072 KiB 
           flags: lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 18089 
           Speed: 1463 MHz min/max: 1199/2267 MHz Core speeds (MHz): 1: 1263 2: 1355 3: 1403 4: 1358 
Graphics:  Device-1: Intel Core Processor Integrated Graphics vendor: Acer Incorporated ALI driver: i915 v: kernel 
           bus ID: 00:02.0 
           Display: x11 server: X.Org 1.20.8 driver: modesetting unloaded: fbdev,vesa resolution: 1366x768~60Hz 
           OpenGL: renderer: Mesa DRI Intel HD Graphics (ILK) v: 2.1 Mesa 20.0.8 direct render: Yes 
Audio:     Device-1: Intel 5 Series/3400 Series High Definition Audio vendor: Acer Incorporated ALI driver: snd_hda_intel 
           v: kernel bus ID: 00:1b.0 
           Sound Server: ALSA v: k5.4.0-42-generic 
Network:   Device-1: Broadcom and subsidiaries NetLink BCM57780 Gigabit Ethernet PCIe vendor: Acer Incorporated ALI 
           driver: tg3 v: 3.137 port: 3000 bus ID: 01:00.0 
           IF: enp1s0 state: down mac: <filter> 
           Device-2: Broadcom and subsidiaries BCM43225 802.11b/g/n 
           vendor: Foxconn T77H103.00 Wireless Half-size Mini PCIe Card driver: wl v: kernel port: 3000 bus ID: 02:00.0 
           IF: wlp2s0 state: up mac: <filter> 
Drives:    Local Storage: total: 111.79 GiB used: 36.42 GiB (32.6%) 
           ID-1: /dev/sda vendor: GOODRAM model: N/A size: 111.79 GiB temp: 33 C 
Partition: ID-1: / size: 26.60 GiB used: 18.21 GiB (68.5%) fs: ext4 dev: /dev/sda5 
Sensors:   System Temperatures: cpu: 52.0 C mobo: N/A 
           Fan Speeds (RPM): N/A 
Info:      Processes: 197 Uptime: 14m Memory: 5.49 GiB used: 1.52 GiB (27.7%) Init: systemd runlevel: 5 Compilers: gcc: 9.3.0 
           Shell: bash v: 5.0.17 inxi: 3.0.38

Can anyone help me? Thanks.

[Welcome]

I did a quick search and found these answers (might help):

Anyway, I found a strange "trick" to change the brightness of the monitor, If I want to increase or reduce the brightness, I have first to press these combinations: fn + F6. This one will "close my monitor, then when the monitor is off if I use the following combination of keys: fn + left/right key and after I made the combination, I press a random key to turn back on my monitor. And ofcourse the monitor turns on with different brightness. (Weird..)

https://community.acer.com/en/discussio ... -the-cable

I had the same issue with my Acer Aspire 5740G. How I fixed it.

Solution 1. Change the brightness of your screen (even though you'll see no difference when changing) then turn your screen off and on again with the key Fn+F6. Your brightness will change upon restart! It isn't very convenient but it's better than burning your eyes and it works with the right drivers.

https://community.acer.com/en/discussio ... spire-5740

Another option is to use xgamma, although it's really supposed to be for gamma correction.

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xgamma                                         # outputs Red  1.000, Green  1.000, Blue  1.000 (default values)
xgamma -gamma 0.8                              # a touch darker
xgamma -gamma 0.7                              # maybe not what you want
xgamma -rgamma .95 -ggamma 1.0 -bgamma 1.05    # too bright? 
xgamma -rgamma 0.90 -ggamma 0.83 -bgamma 0.74  # warm display with nice saturation
xgamma -gamma 1.0                              # returned to original settings!

To try xgamma, open a terminal window, select and copy the command you want to try, and then paste the command into the terminal window. Hope this help!

[94d4a788df]

I found working solution: https://itsfoss.com/fix-brightness-ubuntu-1310/

[Welcome]

Thanks for the update and link! It was an interesting post, and the 697 comments at that post are interesting, too. Some reported that the fix worked, some reported it didn't work, and others had different suggested fixes.

If possible, please add the word [SOLVED] to the title of the first post of this thread. Thanks!

[7rocks]

Tried this on a Toshiba Dynabook product: PORTEGE X30L-J.

Did not work.

[cipricus]

Tried this on a Toshiba Dynabook product: PORTEGE X30L-J.

Did not work.

This worked for me on a HP: https://askubuntu.com/a/1311344/925128