Greetings,
fresh install of CentOS 7 (1611) 64bit on a Lenovo Z570(i7-2670QM CPU @ 2.20GHz). The 'Fn' brightness keys bring up the brightness gnome applet but the screen brightness does not change... same from the power settings screen brightness control.
lsapi | grep VGA output:
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
dmesg | grep -i video output:
[ 1.909117] pci 0000:00:02.0: Boot video device
[ 2.978471] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no)
[ 3.959920] input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A08:00/LNVIDEO:01/input/input5
[ 13.084060] acer_wmi: Brightness must be controlled by acpi video driver
[ 16.037554] Linux video capture interface: v2.00
[ 16.286952] uvcvideo: Found UVC 1.00 device Lenovo EasyCamera (058f:a006)
[ 16.290317] usbcore: registered new interface driver uvcvideo
[ 16.290321] USB Video Class driver (1.1.1)
[ 668.638407] video LNXVIDEO:01: Restoring backlight state
[ 1068.398237] video LNXVIDEO:01: Restoring backlight state
dmesg | grep -i vga output:
[ 1.892690] vgaarb: device added: PCI:0000:00:02.0,decodes=io+mem,owns=io+mem,locks=none
[ 1.892693] vgaarb: loaded
[ 1.892694] vgaarb: bridge control possible 0000:00:02.0
[ 2.449533] fb0: EFI VGA frame buffer device
[ 2.755678] fb: conflicting fb hw usage inteldrmfb vs EFI VGA - removing generic driver
[ 2.755789] [drm] Replacing VGA console driver
[ 2.762169] vgaarb: device changed decodes: PCI:0000:00:02.0,olddecodes=io+mem,decodes=io+mem:owns=io+mem
Please help. The screen is so bright it makes my eyes hurt.
Please let me know if you need any other details.
thank you
Edit: Following is the workaround i found that worked for me:
echo 100 > /sys/class/backlight/intel_backlight/brightness
hope it helps anyone with the same problem.