Dell Laptop Keyboard Illumination

I bought a refurbished Dell 7420e laptop to replace my aging Dell 7470. The 7470 has an S key that works irregularly.

Dell laptops have a “backlight”, and the letters on the black-body of the keys can glow under the right circumstances. Very handy when positioning your fingers on the keyboard when in dim rooms. After installing Arch Linux, the 7420e keyboard would not illuminate. The keyboard backlight worked, the POST flashed it during reboots.

The (rightly famed) Arch Linux wiki has an article that includes a section on Dell laptops which recommends libsmbios. libsmbios is available in the Arch package repositories, but did not help. The smbios-keyboard-ctl program claimed an ERROR: Could not execute SMI. None of the alternatives the help text listed, worked. The kernel modules were already loaded, I ran it as root, etc etc etc.

The Arch Linux wiki had a further suggestion, a Dell provided utility dell-command-configure, which has an AUR package.

AUR packages always seem slightly sketchy to me, but I did download the “snapshot”, and built it. I had to change the PKGBUILD file to eliminate a dependency on an old version of openssl.

Here’s the “after” state of the line in PKGBUILD:

depends=('bash' 'libsmbios' 'openssl' 'pciutils')

There’s an Arch Linux Forum post about dell-command-configure messing up initrd files so they’re unbootable, but I do not see a file /opt/dell/dcc/libcrypto.so.3 so I’m going to risk leaving it installed.

The cctk commands of note are:

$ sudo cctk --KeyboardIllumination                                        # /home/bediger/nblog

That one shows you the current keyboard backlight state. I didn’t write it down, but I recall my 7420e initially said “disabled” or something, suggesting that there’s a BIOS setting.

$ sudo cctk --KeyboardIllumination=Bright

The command above set keyboard backlight so I could see it. The backlight turns on when I caress the trackpad, and turns off after a few seconds of idle. That’s exactly what I wanted.

I believe there were “Dim” and “Auto” options as well. I didn’t try them.