Multi monitor -- Brightness control

[R_S]

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.
Is there any setting to adjust to enable the brightness control?

Endeavour OS (Kernel 6.17.8), Gnome 49.1, Wayland

R_S

[skeller (Sebastian Keller)]

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]

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 (Deref)]

Brightness control using ddcutil - GNOME Shell Extensions

I use this extension to control the brightness of my second monitor

[astr64]

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 (Sebastian Keller)]

If you only have a brightness device for the internal screen, you could try the ddcci driver.

[R_S]

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

[Yeshey]

Same thing is happening to me.

find /sys -iname brightness 2>/dev/null | grep drm only gives me the one:
/sys/devices/pci0000:00/0000:00:02.0/drm/card1/card1-eDP-1/intel_backlight/brightness

I saw that this was merged: udev: Use any parent of a backlight, as long as it is a drm_connector (!4763) · Merge requests · GNOME / mutter · GitLab

So I tried the latest gnomeOS from here: https://os.gnome.org/

But it still wouldn’t detect my second screen:

Edit: I just saw the latest comment there: udev: Use any parent of a backlight, as long as it is a drm_connector (!4763) · Merge requests · GNOME / mutter · GitLab, and apparantly the solution is not currently expected to work with nvidia, witch is my case, so that might be the problem

[skeller (Sebastian Keller)]

Also I don’t think GNOME OS includes the out of tree ddcci-driver-linux driver. So this would be an additional reason why it won’t work.