Cannot adjust display brighness

[Leviathan]

I have installed Manjaro KDE just today and it’s fully updated and upgraded
The problem is I can not adjust the display brightness using power management window or using Fn key:
My inxi -G output

Device-1: Intel 2nd Generation Core Processor Family Integrated Graphics driver: i915 v: kernel
           Device-2: NVIDIA GF108M [GeForce GT 540M] driver: N/A
           Device-3: Alcor Micro USB 2.0 PC Camera type: USB driver: uvcvideo
           Display: x11 server: X.Org 1.20.13 driver: loaded: intel resolution: 1366x768~60Hz
           OpenGL: renderer: Mesa DRI Intel HD Graphics 3000 (SNB GT2) v: 3.3 Mesa 21.2.3

[cscs]

It would be better if you provided the full output of inxi:

How to provide good information

Welcome to Manjaro! To allow all of us helpful people on this forum TO HELP YOU, we need some basic information about your system. This probably means you described the symptoms of your problem, but now we need some more information to know where the origin of your issue is exactly. Someone else probably linked you to this tutorial, so if you’re reading this in response to a question, please click the link above this text to bring you to the full and unabridged text of the tutorial…

[Leviathan]

inxi --full

System:    Host: mehdi Kernel: 5.13.19-2-MANJARO x86_64 bits: 64 Desktop: KDE Plasma 5.22.5 Distro: Manjaro Linux
Machine:   Type: Laptop System: Acer product: Aspire 5755G v: V1.14 serial: <superuser required>
           Mobo: Acer model: JV51_HR serial: <superuser required> BIOS: Acer v: 1.14 date: 09/07/2011
Battery:   ID-1: BAT0 charge: 40.9 Wh (100.0%) condition: 40.9/48.8 Wh (83.7%)
CPU:       Info: Dual Core model: Intel Core i5-2430M bits: 64 type: MT MCP cache: L2: 3 MiB
           Speed: 798 MHz min/max: 800/3000 MHz Core speeds (MHz): 1: 798 2: 798 3: 798 4: 798
Graphics:  Device-1: Intel 2nd Generation Core Processor Family Integrated Graphics driver: i915 v: kernel
           Device-2: NVIDIA GF108M [GeForce GT 540M] driver: N/A
           Device-3: Alcor Micro USB 2.0 PC Camera type: USB driver: uvcvideo
           Display: x11 server: X.Org 1.20.13 driver: loaded: intel resolution: 1366x768~60Hz
           OpenGL: renderer: Mesa DRI Intel HD Graphics 3000 (SNB GT2) v: 3.3 Mesa 21.2.3
Audio:     Device-1: Intel 6 Series/C200 Series Family High Definition Audio driver: snd_hda_intel
           Device-2: NVIDIA GF108 High Definition Audio driver: snd_hda_intel
           Sound Server-1: ALSA v: k5.13.19-2-MANJARO running: yes
           Sound Server-2: PulseAudio v: 15.0 running: yes
           Sound Server-3: PipeWire v: 0.3.38 running: yes
Network:   Device-1: Broadcom NetLink BCM57785 Gigabit Ethernet PCIe driver: tg3
           IF: enp2s0f0 state: down mac: b8:70:f4:f9:e3:24
           Device-2: Qualcomm Atheros AR9287 Wireless Network Adapter driver: ath9k
           IF: wlp3s0 state: up mac: XXXXXXXXXX
Bluetooth: Device-1: Foxconn / Hon Hai Bluetooth USB Host Controller type: USB driver: btusb
           Report: rfkill ID: hci0 state: up address: see --recommends
Drives:    Local Storage: total: 231.07 GiB used: 8.66 GiB (3.7%)
           ID-1: /dev/sda vendor: Patriot model: Burst size: 223.57 GiB
           ID-2: /dev/sdb type: USB vendor: SMI (STMicroelectronics) model: USB size: 7.5 GiB
Partition: ID-1: / size: 49.68 GiB used: 8.66 GiB (17.4%) fs: ext4 dev: /dev/sda7
Swap:      Alert: No swap data was found.
Sensors:   System Temperatures: cpu: 53.0 C mobo: N/A
           Fan Speeds (RPM): N/A
Info:      Processes: 206 Uptime: 1h 12m Memory: 5.66 GiB used: 2.13 GiB (37.7%) Shell: Zsh inxi: 3.3.07

[cscs]

But thats not what is recommended … for a number of reasons, including you exposed your network mac addresses. Please use the linked instructions.

[Leviathan]

Thanks for the note
Prev post is edited.
inxi -Fazy:

System:
  Kernel: 5.13.19-2-MANJARO x86_64 bits: 64 compiler: gcc v: 11.1.0
  parameters: BOOT_IMAGE=/boot/vmlinuz-5.13-x86_64
  root=UUID=1d465d26-79f4-492e-bdf5-0f734e324362 rw quiet apparmor=1
  security=apparmor udev.log_priority=3
  Desktop: KDE Plasma 5.22.5 tk: Qt 5.15.2 wm: kwin_x11 vt: 1 dm: SDDM
  Distro: Manjaro Linux base: Arch Linux
Machine:
  Type: Laptop System: Acer product: Aspire 5755G v: V1.14 serial: <filter>
  Chassis: type: 10 v: 1.14 serial: <filter>
  Mobo: Acer model: JV51_HR serial: <filter> BIOS: Acer v: 1.14
  date: 09/07/2011
Battery:
  ID-1: BAT0 charge: 40.9 Wh (100.0%) condition: 40.9/48.8 Wh (83.7%)
  volts: 12.5 min: 11.1 model: SANYO Li_Ion_4000mA type: Li-ion
  serial: <filter> status: Full
CPU:
  Info: Dual Core model: Intel Core i5-2430M bits: 64 type: MT MCP
  arch: Sandy Bridge family: 6 model-id: 2A (42) stepping: 7 microcode: 2F
  cache: L2: 3 MiB
  flags: avx lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx bogomips: 19162
  Speed: 798 MHz min/max: 800/3000 MHz Core speeds (MHz): 1: 798 2: 817 3: 798
  4: 798
  Vulnerabilities: Type: itlb_multihit status: KVM: VMX disabled
  Type: l1tf
  mitigation: PTE Inversion; VMX: conditional cache flushes, SMT vulnerable
  Type: mds mitigation: Clear CPU buffers; SMT vulnerable
  Type: meltdown mitigation: PTI
  Type: spec_store_bypass
  mitigation: Speculative Store Bypass disabled via prctl and seccomp
  Type: spectre_v1
  mitigation: usercopy/swapgs barriers and __user pointer sanitization
  Type: spectre_v2 mitigation: Full generic retpoline, IBPB: conditional,
  IBRS_FW, STIBP: conditional, RSB filling
  Type: srbds status: Not affected
  Type: tsx_async_abort status: Not affected
Graphics:
  Device-1: Intel 2nd Generation Core Processor Family Integrated Graphics
  vendor: Acer Incorporated ALI driver: i915 v: kernel bus-ID: 00:02.0
  chip-ID: 8086:0116 class-ID: 0300
  Device-2: NVIDIA GF108M [GeForce GT 540M] driver: N/A
  alternate: nouveau, nvidia_drm, nvidia bus-ID: 01:00.0 chip-ID: 10de:0df4
  class-ID: 0300
  Device-3: Alcor Micro USB 2.0 PC Camera type: USB driver: uvcvideo
  bus-ID: 1-1.3:3 chip-ID: 058f:3821 class-ID: 0e02
  Display: x11 server: X.Org 1.20.13 compositor: kwin_x11 driver:
  loaded: intel display-ID: :0 screens: 1
  Screen-1: 0 s-res: 1366x768 s-dpi: 96 s-size: 361x203mm (14.2x8.0")
  s-diag: 414mm (16.3")
  Monitor-1: LVDS1 res: 1366x768 hz: 60 dpi: 102 size: 340x190mm (13.4x7.5")
  diag: 389mm (15.3")
  OpenGL: renderer: Mesa DRI Intel HD Graphics 3000 (SNB GT2)
  v: 3.3 Mesa 21.2.3 compat-v: 3.0 direct render: Yes
Audio:
  Device-1: Intel 6 Series/C200 Series Family High Definition Audio
  vendor: Acer Incorporated ALI driver: snd_hda_intel v: kernel
  bus-ID: 00:1b.0 chip-ID: 8086:1c20 class-ID: 0403
  Device-2: NVIDIA GF108 High Definition Audio driver: snd_hda_intel v: kernel
  bus-ID: 01:00.1 chip-ID: 10de:0bea class-ID: 0403
  Sound Server-1: ALSA v: k5.13.19-2-MANJARO running: yes
  Sound Server-2: JACK v: 1.9.19 running: no
  Sound Server-3: PulseAudio v: 15.0 running: yes
  Sound Server-4: PipeWire v: 0.3.38 running: yes
Network:
  Device-1: Broadcom NetLink BCM57785 Gigabit Ethernet PCIe
  vendor: Acer Incorporated ALI driver: tg3 v: kernel port: N/A
  bus-ID: 02:00.0 chip-ID: 14e4:16b5 class-ID: 0200
  IF: enp2s0f0 state: down mac: <filter>
  Device-2: Qualcomm Atheros AR9287 Wireless Network Adapter
  vendor: Foxconn T77H167.00 driver: ath9k v: kernel bus-ID: 03:00.0
  chip-ID: 168c:002e class-ID: 0280
  IF: wlp3s0 state: up mac: <filter>
Bluetooth:
  Device-1: Foxconn / Hon Hai Bluetooth USB Host Controller type: USB
  driver: btusb v: 0.8 bus-ID: 1-1.6:5 chip-ID: 0489:e03c class-ID: e001
  serial: <filter>
  Report: rfkill ID: hci0 rfk-id: 3 state: up address: see --recommends
Drives:
  Local Storage: total: 231.07 GiB used: 8.66 GiB (3.7%)
  SMART Message: Unable to run smartctl. Root privileges required.
  ID-1: /dev/sda maj-min: 8:0 vendor: Patriot model: Burst size: 223.57 GiB
  block-size: physical: 512 B logical: 512 B speed: 6.0 Gb/s type: SSD
  serial: <filter> rev: 61.3 scheme: MBR
  ID-2: /dev/sdb maj-min: 8:16 type: USB vendor: SMI (STMicroelectronics)
  model: USB size: 7.5 GiB block-size: physical: 512 B logical: 512 B
  type: N/A serial: <filter> rev: 1100 scheme: MBR
  SMART Message: Unknown USB bridge. Flash drive/Unsupported enclosure?
Partition:
  ID-1: / raw-size: 50.78 GiB size: 49.68 GiB (97.84%) used: 8.66 GiB (17.4%)
  fs: ext4 dev: /dev/sda7 maj-min: 8:7
Swap:
  Alert: No swap data was found.
Sensors:
  System Temperatures: cpu: 51.0 C mobo: N/A
  Fan Speeds (RPM): N/A
Info:
  Processes: 209 Uptime: 1h 18m wakeups: 2 Memory: 5.66 GiB
  used: 2.18 GiB (38.5%) Init: systemd v: 249 tool: systemctl Compilers:
  gcc: N/A Packages: pacman: 1207 lib: 333 flatpak: 0 Shell: Zsh v: 5.8
  default: Bash v: 5.1.8 running-in: yakuake inxi: 3.3.07

[cscs]

A few quick things …
Your BIOS is out of date and your kernel is EOL.
These may or may not be related, but they are worth mentioning.

[Leviathan]

I’m not sure if update these two will help
worth updating later maybe

[cscs]

I guess a simple check is to install xorg-xbacklight

And see if the following work:

xbacklight -inc 10
xbacklight -dec 10

(this is more just to see if the backlight is easily controllable)

[Leviathan]

Yes sir
It’s working
I can change using these two commands.
But how can I do it normally?