Backlight always at 100% Fedora 35 NVIDIA (495.44) Kernel: 5.14.16-301 Intel i7-11800H & RTX 3060m

Graphics / Linux Linux
1

I got my brand new Tuxedo Stellaris 15 and everything works perfectly fine beside the backlight which is always at 100%…
nvidia-bug-report.log.gz (365.8 KB)

Installation was done via RPM Fusion and here the commands:

dnf install kernel-devel xorg-x11-drv-nvidia akmod-nvidia
dnf install xorg-x11-drv-nvidia-cuda
dnf install vdpauinfo libva-vdpau-driver libva-utils

I also tried all the “solutions” with vendor, none…
I also tried nvidia.NVreg_RegistryDwords=EnableBrightnessControl=1
but this just added nvidia0 under /sys but brightness control still was not working…
also with vendor I just got vendor0 and vendor1 but non of them can change it…

Well maybe the reason why it work for all the other with the new driver is that they may have an older Intel CPU? Is it now due to Tiger lake (11th Gen.)

2

The panel is connected to the intel gpu, so there should be
/sys/class/backlight/intel_backlight
Is that missing? What folders are in /sys/class/backlight?

3

[root@fedora ~]# ll /sys/class/backlight/
total 0
lrwxrwxrwx. 1 root root 0 Nov 11 14:54 intel_backlight → …/…/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight
[root@fedora ~]# ll /sys/class/backlight/intel_backlight/
total 0
-r–r–r–. 1 root root 4096 Nov 11 13:54 actual_brightness
-rw-r–r–. 1 root root 4096 Nov 11 17:19 bl_power
-rw-r–r–. 1 root root 4096 Nov 11 16:23 brightness
lrwxrwxrwx. 1 root root 0 Nov 11 17:19 device → …/…/card0-eDP-1
-r–r–r–. 1 root root 4096 Nov 11 13:54 max_brightness
drwxr-xr-x. 2 root root 0 Nov 11 13:54 power
-r–r–r–. 1 root root 4096 Nov 11 17:19 scale
lrwxrwxrwx. 1 root root 0 Nov 11 14:54 subsystem → …/…/…/…/…/…/…/class/backlight
-r–r–r–. 1 root root 4096 Nov 11 13:54 type
-rw-r–r–. 1 root root 4096 Nov 11 14:54 uevent

4

Does that work if you write to it as root?
If so, does the kernel parameter
video.use_native_backlight=1
help with setting through keyboard/gnome?

5

As mentioned I can write whatever I want into brightness it does not change
Keys are not working as well as writing into brightnis in whatever combination or however I adjust it via kernel args.
Of course I get other devices under /sys/class/backlight/ but it does not change that it is not honoring my/anyvalues ;-(

6

Ok, intel_backlight is there, the only one but not working. Please try kernel parameter
i915.enable_dpcd_backlight=1

7

I also tested this one in the past but with an additional parameter I think none, so I did it again, but no change…

[root@fedora ~]# cd /sys/class/backlight/
[root@fedora backlight]# ll
total 0
lrwxrwxrwx. 1 root root 0 Nov 11 2021 intel_backlight → …/…/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight
[root@fedora backlight]# cat intel_backlight/max_brightness
512
[root@fedora backlight]# echo “50” intel_backlight/brightness
50 intel_backlight/brightness
[root@fedora backlight]# echo “500” intel_backlight/brightness
500 intel_backlight/brightness
[root@fedora backlight]# dmesg | grep -i i915
[ 0.000000] Command line: BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.16-301.fc35.x86_64 root=UUID=3f93ca69-acd9-4a7d-98f6-f9ae374ead12 ro rootflags=subvol=root rhgb quiet rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 i915.enable_dpcd_backlight=1
[ 0.343356] Kernel command line: BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.16-301.fc35.x86_64 root=UUID=3f93ca69-acd9-4a7d-98f6-f9ae374ead12 ro rootflags=subvol=root rhgb quiet rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 i915.enable_dpcd_backlight=1

8

Rather use

sudo -s
echo 50 > /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness

you missed the ‘>’

9

usually I always do a cat to verify… once I did it not I forgot > xD

however no change:
[root@fedora ~]# dmesg | grep -i dpcd
[ 0.000000] Command line: BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.16-301.fc35.x86_64 root=UUID=3f93ca69-acd9-4a7d-98f6-f9ae374ead12 ro rootflags=subvol=root rhgb quiet rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 i915.enable_dpcd_backlight=1
[ 0.343162] Kernel command line: BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.14.16-301.fc35.x86_64 root=UUID=3f93ca69-acd9-4a7d-98f6-f9ae374ead12 ro rootflags=subvol=root rhgb quiet rd.driver.blacklist=nouveau modprobe.blacklist=nouveau nvidia-drm.modeset=1 i915.enable_dpcd_backlight=1
[root@fedora ~]# cat /sys/class/backlight/intel_backlight/brightness
312
[root@fedora ~]# echo “50” > /sys/class/backlight/intel_backlight/brightness
[root@fedora ~]# echo “500” > /sys/class/backlight/intel_backlight/brightness
[root@fedora ~]# cat /sys/class/backlight/intel_backlight/brightness
500
[root@fedora ~]# echo “50” > /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness
[root@fedora ~]# cat /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness
50

10

No idea. Rather contact Tuxedo, maybe they know what’s going on.

11

Works with
i915.enable_dpcd_backlight=0

12

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