Controlling Screen brightness on an iMac 21,5" (late-2012) doesn't work

Regarding the brightness control, It’ll come back in the next Fedora version, afaik. Hans was talking about it trying to release re-introduce the support in kernel 6.2 (Which will be in Fedora 38, I think)

Regarding the graphics driver, I’m sticking to the nuoveau-driver, since it’s more matured and stable compared to the old nVidia driver. I also had a lot of issues with the nVidia driver.

this morning, kernel updates to 6.2.7-300.fc38.x86_64 on Fedora 38.

The problem is still there : no brightness control.

Thank you for sharing. Well, at least they’re aware and working on it. :slight_smile:

So, Fedora 37 Desktop also just moved to Kernel 6.2… Unfortunately, the fix wasn’t included.

Have you checked for ddcutil support? It does work on my late 2013 iMac.

I assume that ongoing efforts to support brightness control (needed due to the morass of vendor-specific methods) will use MCCS (Monitor Control Command Set) when available.

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This morning, the kernel updated on fedora 38 to version 6.2.11 and… the brightness control finally works!

Now, brightness changes from the keyboard and from gnome menu on the top right of the window. I still don’t see the control bar in gnome settings.

Thank you linux devs.

Remember, the kernel and gnome developers are different groups. A fix in the kernel may not be seen in gnome for some time as that is a separate issue with a different fix.

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The control popped back in, when the Kernel regressed though.

However, it still isn’t fixed but I noticed the default screen brightness is now about ~75% in stead of ~25% brightness, while it’s still not controllable.

I have an iMac14,2, (late 2013, 27") I see:

% journalctl -b -g bright
Jul 15 10:34:51 fedorausb systemd[1]: Starting systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0...
Jul 15 10:34:51 fedorausb systemd[1]: Finished systemd-backlight@backlight:acpi_video0.service - Load/Save Screen Backlight Brightness of backlight:acpi_video0.

I was using ddcutil until the Gnome Settings brightness control appeared. I have noticed some erratic changes, but I suspect they are tied to the room light level (north facing windows in Northern hemisphere location) affected by passing clouds. The backlight level changes if I put my thumb over the camera.

I have a 2011 iMac and this fixed it. I’m able to fully control the brightness.
And yes…I resurrected this thread to post this.

sudo grubby --update-kernel=ALL --args=“acpi_backlight=native”