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pop-os / linux

Pop!_OS fork of https://launchpad.net/ubuntu/+source/linux
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serw12 has no backlight control on 6.x #190

Open jacobgkau opened 1 year ago

jacobgkau commented 1 year ago

On the serw12 running kernel 6.x (6.0.2 and 6.0.6), the screen backlight is stuck at maximum brightness regardless of what I set the brightness to using the hotkeys/GUI. I have a directory at /sys/class/backlight/acpi_video0/ showing a brightness number that does increase/decrease as I change the setting, and one at /sys/class/backlight/acpi_video1/ that has a brightness always reporting 0.

On kernel 5.19 (with working backlight control), I have ls -alh /sys/class/backlight/nvidia_0/ and not the other two directories.

leviport commented 1 year ago

FWIW, the lab unit is still working as expected. I suspect this has something to do with the LCD panel change that happened partway through serw12's production period.

jacobgkau commented 1 year ago

I seem to have backlight control on 6.0.6-76060006-generic (d2df702) today, so it may have been something else.

Could be a combination of an older NVIDIA driver version and the kernel version, since I upgraded the NVIDIA driver to test https://github.com/pop-os/system76-driver/issues/218. It seems not automatically performing NVIDIA driver upgrades (while still generally expecting users to have the latest version) can cause some problems.

sntnlz75 commented 1 year ago

Confirming that the issue is no longer present after manually updating the NVIDIA driver to 515.65.01 (from 470.41.03) on the same kernel version noted by @jacobgkau. Hotkey backlight control is possible again after only being possible by directly setting values in a terminal with xrandr recently.