[SOLVED] Brightness Down key no longer working

[Jacksaur]

This happened out of nowhere recently. My laptop's brightness down hotkey does absolutely nothing, whilst my brightness Up key works perfectly.
Below is the output of XEV, pushing my Brightness Down key once and Brightness Up once afterwards.

The KeymapNotify event lines only appear with my Brightness Up key, replacing the KeyPress event that shows up with Brightness Down. So I'm assuming that's where things are going wrong.

[claydoh]

Laptop? External KB? Does it work elsewhere?

If a laptop, the keys have a strong change of controlling the hardware directly via acpi as opposed to keyboard shortcuts running commands/xorg events, and if an external kb, it still may be doing this for some actions.

.

$ acpi_listen
button/volumeup VOLUP 00000080 00000000 K
button/volumeup VOLUP 00000080 00000000 K
button/volumedown VOLDN 00000080 00000000 K
cd/play CDPLAY 00000080 00000000 K
button/mute MUTE 00000080 00000000 K
button/mute MUTE 00000080 00000000 K

[DoYouKubuntu]

This happened out of nowhere recently. My laptop's brightness down hotkey does absolutely nothing, whilst my brightness Up key works perfectly.

Which keys are used for brightness up and down? Just FYI, on my laptop they're [Fn][F8] for down and [Fn][F9] for up.

Have you tried resetting the key(s)? Or adding custom shortcuts? Start here and poke around:
Main Menu | Settings | System Settings | Shortcuts | Shortcuts | Power Management

What do you see for increase/decrease screen brightness?

If you want to assign fresh keys--which, of course, can be the same one(s) you're used to--use the "Add custom shortcut" button on the 'decrease screen brightness' page. If you enter the key(s) you normally use, and it tells you they're already in use and do you want to re-assign them, just say yes. Make sure you apply/save your changes and then exit from settings.

Let us know if this works.

[Jacksaur]

Laptop? External KB? Does it work elsewhere?

If a laptop, the keys have a strong change of controlling the hardware directly via acpi as opposed to keyboard shortcuts running commands/xorg events, and if an external kb, it still may be doing this for some actions.

Laptop. It worked fine for months previously and XEV names the key properly, so I'm assuming it did things the "right" way. It definitely triggered the KDE GUI and everything.

Have you tried resetting the key(s)? Or adding custom shortcuts? Start here and poke around:
Main Menu | Settings | System Settings | Shortcuts | Shortcuts | Power Management

Well huh. It's got the key listed there and it's disabled. Even has the "Changed setting" marker beside it. Yet I've never entered this menu before at all, curious.
Regardless, ticking the box again and applying fixed my problem immediately. And I had no idea there was a section like this with all the system shortcuts rebindable in one place. Thanks for mentioning it!

[DoYouKubuntu]

Have you tried resetting the key(s)? Or adding custom shortcuts? Start here and poke around:
Main Menu | Settings | System Settings | Shortcuts | Shortcuts | Power Management

Well huh. It's got the key listed there and it's disabled. Even has the "Changed setting" marker beside it. Yet I've never entered this menu before at all, curious.
Regardless, ticking the box again and applying fixed my problem immediately. And I had no idea there was a section like this with all the system shortcuts rebindable in one place. Thanks for mentioning it!

You're welcome! I'm glad it's fixed.

There's a plethora of settings to explore...when you have some time to kill, you can easily get lost just perusing them and experimenting!