External monitor brightness control

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1

Hello!
I am very new to Fedora and insofar, it feels like the smoothest experience ever!
I just have an issue with my external monitor brightness control. I do have the physical button but the screen is fairly away and I have to go to 2 submenus to adjust brightness so I really don´t want to be doing this every day. I used to have a GUI interface on my mac OS before called monitor control which did the job nicely but apparently several gui interface I have tried (brightness controller and a couple of other) do not manage to modify the brightness. Apparently it is due to Wayland, which also render the xrandr option irrelevant.
My question is the following: is there any gui or cli way of easily adjusting the brightness of my external monitor?
Thank you for your time!

2

ddcutil is working for me (I’m running Sway).

3

Thank you for your answer. When running ddcutil detect I get teh following error:
Device /dev/i2c-0 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-1 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-2 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-3 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-4 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-5 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-6 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-7 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-8 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-9 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-10 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-11 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-12 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-13 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-14 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-15 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-16 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-17 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-18 is not readable and writable. Error = EACCES(13): Permission denied
Device /dev/i2c-19 is not readable and writable. Error = EACCES(13): Permission denied
Devices possibly used for DDC/CI communication cannot be opened: /dev/i2c-0 /dev/i2c-1 /dev/i2c-2 /dev/i2c-3 /dev/i2c-4 /dev/i2c-5 /dev/i2c-6 /dev/i2c-7 /dev/i2c-8 /dev/i2c-9 /dev/i2c-10 /dev/i2c-11 /dev/i2c-12 /dev/i2c-13 /dev/i2c-14 /dev/i2c-15 /dev/i2c-16 /dev/i2c-17 /dev/i2c-18 /dev/i2c-19
See I2C Device Permissions - ddcutil Documentation
No displays found.
Run “ddcutil environment” to check for system configuration problems.

4

Sorry, I should have mentioned that I ran it as “root”. Does prefixing sudo make it work?

Edit: This is what I see, FWIW:

$ sudo ddcutil --display 1 capabilities                                                                                                                                                           
Model: P2419H
MCCS version: 2.1
Commands:
   Op Code: 01 (VCP Request)
   Op Code: 02 (VCP Response)
   Op Code: 03 (VCP Set)
   Op Code: 07 (Timing Request)
   Op Code: 0C (Save Settings)
   Op Code: E3 (Capabilities Reply)
   Op Code: F3 (Capabilities Request)
VCP Features:
   Feature: 02 (New control value)
   Feature: 04 (Restore factory defaults)
   Feature: 05 (Restore factory brightness/contrast defaults)
   Feature: 08 (Restore color defaults)
   Feature: 10 (Brightness)
   Feature: 12 (Contrast)
   Feature: 14 (Select color preset)
      Values:
         05: 6500 K
         08: 9300 K
         0b: User 1
         0c: User 2
   Feature: 16 (Video gain: Red)
   Feature: 18 (Video gain: Green)
   Feature: 1A (Video gain: Blue)
   Feature: 52 (Active control)
   Feature: 60 (Input Source)
      Values:
         01: VGA-1
         0f: DisplayPort-1
         11: HDMI-1
   Feature: AA (Screen Orientation)
      Values:
         01: 0 degrees
         02: 90 degrees
         04: 270 degrees
   Feature: AC (Horizontal frequency)
   Feature: AE (Vertical frequency)
   Feature: B2 (Flat panel sub-pixel layout)
   Feature: B6 (Display technology type)
   Feature: C6 (Application enable key)
   Feature: C8 (Display controller type)
   Feature: C9 (Display firmware level)
   Feature: CC (OSD Language)
      Values:
         02: English
         03: French
         04: German
         06: Japanese
         09: Russian
         0a: Spanish
         0d: Chinese (simplified / Kantai)
         0e: Portuguese (Brazil)
   Feature: D6 (Power mode)
      Values:
         01: DPM: On,  DPMS: Off
         04: DPM: Off, DPMS: Off
         05: Write only value to turn off display
   Feature: DC (Display Mode)
      Values:
         00: Standard/Default mode
         03: Movie
         05: Games
   Feature: DF (VCP Version)
   Feature: E0 (Manufacturer specific feature)
   Feature: E1 (Manufacturer specific feature)
   Feature: E2 (Manufacturer specific feature)
      Values: 00 02 04 0E 12 14 1D (interpretation unavailable)
   Feature: F0 (Manufacturer specific feature)
      Values: 00 0C (interpretation unavailable)
   Feature: F1 (Manufacturer specific feature)
   Feature: F2 (Manufacturer specific feature)
   Feature: FD (Manufacturer specific feature)
5

It does, I do get the external monitor returned and I can change with sudo ddcutil setvcp 10 , thanks!

6

To make it even easier, I set an alias by running the command

alias setbright='ddcutil setvcp 10'

so next time I only need to type setbright

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