# Samsung Notebook: Display brightness issues



## UncleBAZINGA (Oct 29, 2015)

Hi all,

I'm using a Samsung NP530U3C notebook (Core i3 3217U, HD Graphics 4000) with 10.2-RELEASE/GENERIC.

Display brightness can't be adjusted via fn keys, but via terminal i.e. `intel_backlight <value>` works
`sysctl hw.acpi.video.lcd0.brightness=<value>` also works

I want to control it via the fn keys and alternatively i.e. via Xfce4, but the appropriate options aren't displayed in xfce-power-manager panel. The display brightness settings are completely missing:






After booting the system, display brightness is ca. at 80%, when pulling the power cable and relying on battery it is somewhat around 20% I suppose.

Any advice would be much appreciated. Many thanks in advance.


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## lme@ (Oct 30, 2015)

Do the Fn keys produce any event? Try running `xev` from a terminal, then press the buttons and check if you can see anything in the terminal.
If you do, you can make the keys run some script which sets display brightness via sysctl and sudo.


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## UncleBAZINGA (Oct 31, 2015)

I have only one fn key and it doesn't produce an event via xev nor in combination with any of the according fn functions except for audio volume (which is F6-F9 for mute, vol+ and vol-). The output for fn + F7 as an example triggers the following via xev:


```
FocusOut event, serial 38, synthetic NO, window 0x2600001,
  mode NotifyGrab, detail NotifyAncestor

FocusIn event, serial 38, synthetic NO, window 0x2600001,
  mode NotifyUngrab, detail NotifyAncestor

KeymapNotify event, serial 38, synthetic NO, window 0x0,
  keys:  2  0  0  0  0  0  0  0  0  0  0  0  0  0  0  8
  0  3  0  0  0  0  0  0  0  0  0  0  0  0  0  0
```

For all other F*-keys pressed in combination with fn key or the fn key pressed solely nothing happens in xev.

IIRC the fn keys for brightness did work once when I had installed KDE, but now I'm using XFCE4. In KDE I had the opportunity to change the display brightness via GUI panels, but XFCE doesn't give me an option for this even though I've installed the according panels/plugins (i.e. intel_backlight, xfce-power-manager).

Update: nvm, the fn+F-keys for brightness aren't working regardless of the DE.


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## tobik@ (Oct 31, 2015)

You said you can control the brightness levels via sysctl, so one other option is to map some other keys to run a script that increases or decreases the brightness levels via sysctl (like what lme@ suggested). You can create a script like:

```
#!/bin/sh
level=`sysctl -n hw.acpi.video.lcd0.brightness`
case $1 in
        up) sysctl -q hw.acpi.video.lcd0.brightness=$(expr $level + 1) ;;
        down) sysctl -q hw.acpi.video.lcd0.brightness=$(expr $level - 1) ;;
        *) echo "usage: $0 up|down" ;;
esac
exit 0
```


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## UncleBAZINGA (Nov 6, 2015)

Thanks, but I think I'll go with graphics/intel-backlight and trying to map it some keys via x11/xbindkeys.


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## UncleBAZINGA (Nov 9, 2015)

Unfortunately this doesn't work. FreeBSD doesn't recognize my fn-key (except for in combination with F6/F7 for Vol+/-). Whether `xev` nor `xbindkeys -k` return something when pressing fn-key + F2/F3 which should be for brightness incr and decr. `xev` returns a keycode, but `xbindkeys -k` returns nothing. Next issue is that when I use `intel_backlight` as $ it gives me an error about the PCI device (?), but when I run it as # it works like a charm.


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## lme@ (Nov 9, 2015)

Use sudo(8) then.


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