Keyboard Backlight brightness value resets to default upon login. (Laptop)

[fortifiedhill]

This bug is present in Ubuntu MATE 16.04, Arch Linux, Solus (Distro I'm on). The bug however is not present in the Debian Stable Mate packages as far as I can remember. This leads me to believe that the bug was introduced somewhere in the development process. The laptop model I'm using is the Dell Inspiron 5447. This bug is similar to one found in Ubuntu 16.04 (Unity DE), but was fixed: https://bugs.launchpad.net/dell-sputnik/+bug/1510344
Thanks for taking the time to look at this report!! :)

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[baem2]

I had the same problem: Keyboard backlight went on on boot, login etc.

debian stretch with mate-settings-daemon v. 1.16.2.

The fix was easy:

Edit /etc/dbus-1/system.d/org.freedesktop.UPower.conf.

Change lines:

<allow send_destination="org.freedesktop.UPower"
send_interface="org.freedesktop.UPower.KbdBacklight"/>

So it looks like:

<deny send_destination="org.freedesktop.UPower"
send_interface="org.freedesktop.UPower.KbdBacklight"/>

Please fix it in the package!

[tidux]

This fix does not work on a MacBookPro11,1 on MATE 1.20. The backlight on my keyboard pops back on at 50% brightness every time the MATE power manager automatically changes my display's brightness in either direction, as well as on login.

[baem2]

After a vanilla installation of debian buster, the problem comes up again. The file org.freedesktop.UPower.conf is not even existing. When copying that file from an older PC, it is fixed again.

[danrobinson78]

This exists in the live session of Ubuntu Mate 19.10. FYI it's the same issue reported on mate-desktop/mate-desktop#306. I don't know if there's a way to merge that bug with this as this is likely where the issue actually lies.

[mike-burns]

This can actually be controlled via d-conf.

1. Open dconf-editor.
2. Navigate to /org/mate/power-manager/kbd-brightness-on-ac.
3. Uncheck "Use default value".
4. Set "Custom value" to 0.

(I had to read the code to learn this.)

[danrobinson78]

I don't think that really solves the issue, it just changes the value that it resets to on login. Ideally it should just keep whatever value is already set on the system.

Seems like the correct solution would be to read the value from sysfs and then have the UI reflect whatever is already there. I think that also might be a better solution for mate-desktop/mate-power-manager#76 as well (although I'm not sure why that is still open since the PR was merged?) and then the behavior would follow how most other DEs handle it.

Especially since systemd by default restores backlight on boot so everything, display manager included, picks it up even before the power manager/settings-daemon is loaded.

[lukefromdc]

It is also important that a brightness value at or near zero never be saved across logins, as this could lock a user out