I am on a Dell XPS 13 7390, shipped with Ubuntu, now on version 20.04.4 LTS.
I am pretty sure that maximum brightness setting, isn't really setting it to max.
I have never tried Windows on this machine, but I have noticed that when I plug the AC power, the screen become brighter, not by a lot, but certainly by a noticeable amount. Regardless of my actual screen brightness level, I can't reach the same brightness as when I am plugged in.
I know there is a pretty similar post here, but not only I already tried the proposed "solutions", even if no one was marked as "solution", but I can't even comment on it as I have not enough "reputation"...
Hence why I am creating a new one.
Now, speaking about what I've already tried:
- Updates
- BIOS update
- Firmware update
- Grub edit, as proposed by the other post (basically broke brightness control level, its fixed to maximum)
- I have no light sensor, so nothing to try.
Speaking of what I won't try:
- Upgrade to latest Ubuntu. Last time everything broke and need to reset it to factory default.
Any help is welcome.
Thanks.