Problems with LCD screen brightness in Thinkpad T420i

One of my computers, the T420i in Trisquel (mate) has a problem that has prevented me from correctly setting the brightness of the screen.

Below I will attach the file with the dmesg data that could be valuable for this case. dmesgfile.txt

Below is the result of: uname -a Linux libre 5.15.0-117-generic #127+11.0trisquel30 SMP Thu Jul 25 03:05:36 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

To be a little more explicit, I want to make known how this affects me:

1. As you turn up the screen glow on the progress bar you look like while I give it up, also go down and then keep climbing.

2. Sometimes when you turn the computer on the screen it stays so dark that I can't even read the text on screen.

3. I have more to add, when I'm on the graphic server and switch to a TTY the brightness is greatly reduced and when the brightness goes up, but when you go back to the graphic server, the brightness drops back.

4. The following command:

   1. lspci -k | grep -EA3 'VGA|3D|Display' give this result: 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) Subsystem: Lenovo 2nd Generation Core Processor Family Integrated Graphics Controller Kernel driver in use: i915 Kernel modules: i915