R_S
November 22, 2025, 5:05pm
1
Hello,
I’ve read, in GNOME 49 the brightness can be adjusted for each monitor independently.
On my system, I connected an external monitor via a USB-C travel hub (LIONWEI) to my laptop. The monitor (Dell) is connected via HDMI to this hub. This monitor is recognized in the settings, but it is not possible to change the brightness.
Settings
Quick menu
Only one slider to adjust the brightness on the Laptop, no possibility to adjust it on the Dell monitor.
Endeavour OS (Kernel 6.17.8), Gnome 49.1, Wayland
R_S
skeller
November 23, 2025, 5:20pm
2
What is the output of find /sys -iname brightness 2>/dev/null | grep drm? This might be Mutter 49 not detecting sysfs backlight (#4421) · Issues · GNOME / mutter · GitLab .
R_S
November 23, 2025, 7:26pm
3
Hello,
the output is (no 2nd monitor connected):
/sys/devices/pci0000:00/0000:00:08.1/0000:04:00.0/drm/card1/card1-eDP-1/amdgpu_bl1/brightness
output with 2nd monitor
/sys/devices/pci0000:00/0000:00:08.1/0000:04:00.0/drm/card1/card1-eDP-1/amdgpu_bl1/brightness
R_S
DerefDev
November 24, 2025, 4:13pm
4
I use this extension to control the brightness of my second monitor
astr64
November 25, 2025, 1:01pm
5
This extension breaks my system really badly. It has a really bad way of chaining ddcutil commands together, which caused so many issues for me.
We should troubleshoot why the official brightness control feature is broken.
I have the same issue - and find /sys -iname brightness 2>/dev/null | grep drm
results in just the laptop screen.
skeller
November 25, 2025, 1:27pm
6
If you only have a brightness device for the internal screen, you could try the ddcci driver .
R_S
November 25, 2025, 2:15pm
7
Connecting the second monitor directly to HDMI on Laptop (no USB C travel hub)
Output
sys/devices/pci0000:00/0000:00:08.1/0000:04:00.0/drm/card1/card1-eDP-1/amdgpu_bl1/brightness
