Anyone knows how to control backlight on a Thinkpad T520 ?

Per olof Ljungmark peo at
Sun Feb 11 21:28:20 UTC 2018

Responding to myself for the sake of completness. It was me...

On 02/06/18 00:46, Per olof Ljungmark wrote:
> It worked with the Fn+<Home><End> on the former TP's I had but not this
> one. It's getting a little old but I love the keyboard and the Nvidia
> graphics.

> Adrian Chadd <adrian at>:
> Does it have more than one gpu in it?

Of course, I've been running with the nvidia chip as default for so long
I forgot about it.

vgapci0: <VGA-compatible display> port 0x5000-0x507f mem
0xf2000000-0xf2ffffff,0xe0000000-0xefffffff,0xf0000000-0xf1ffffff irq 16
at device 0.0 on pci1
nvidia0: <NVS 4200M> on vgapci0
vgapci0: child nvidia0 requested pci_enable_io
vgapci0: child nvidia0 requested pci_enable_io
vgapci0: Boot video device

If I switch the BIOS to Intel as default

vgapci1: <VGA-compatible display> port 0x6000-0x603f mem
0xf1400000-0xf17fffff,0xe0000000-0xefffffff irq 16 at device 2.0 on pci0
drmn1: <Intel SandyBridge (M)> on vgapci1

backlight works in all modes.

Sorry for my negligence.

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